BEIRUT/PARIS The United Nations demanded Syria give its chemical weapons experts immediate access on Thursday to rebel-held Damascus suburbs where poison gas appears to have killed hundreds just a few miles from the U.N. team's hotel.
There was no sign, however, that scientists would soon be taking samples at the scene of horrors that have drawn comparison with the gassing of thousands of Iraqi Kurds at Halabja in 1988.
President Bashar al-Assad's opponents gave death tolls from 500 to well over 1,000 and said more bodies were being found in the wake of Wednesday's mysterious pre-dawn killer fumes, which the Syrian government insists were not its doing.
Images, including some by freelance photographers supplied to Reuters, showed scores of bodies laid out on floors with no visible signs of injury. Some had foam at the nose and mouth.
Talk, notably from France and Britain, of a forceful foreign response remains unlikely to be translated into rapid, concerted action given division between the West and Russia at Wednesday's U.N. Security Council meeting, and caution from Washington on Thursday.
Moscow has said rebels may have released gas to discredit Assad and urged him to agree to a U.N. inspection. On Wednesday, Russian objections to Western pressure on Syria saw the Security Council merely call in vague terms for "clarity" - a position increasingly frustrated Syrian rebels described as "shameful".
On Thursday, U.N. Secretary-General Ban Ki-moon said Syria must let the U.N. team already in Damascus investigate "without delay". He said he would send a top U.N. disarmament official, Angela Kane, to lobby the Syrian government in person.
Ban said he expected a swift, positive answer.
U.S. President Barack Obama has directed U.S. intelligence agencies to urgently help establish what caused the deaths, a State Department spokeswoman said while acknowledging that it may be difficult given the United States does not have diplomatic relations with Syria.
"At this time, right now, we are unable to conclusively determine CW (chemical weapons) use," State Department spokeswoman Jen Psaki told reporters. "We are doing everything possible in our power to nail down the facts," she added.
Former weapons investigators say every hour matters.
"The longer it takes, the easier it is for anybody who has used it to try to cover up," said Demetrius Perricos, who headed the U.N.'s team of weapons inspectors in Iraq in the 2000s.
French Foreign Minister Laurent Fabius said world powers must respond with force if allegations that Syria's government was responsible for the deadliest chemical attack on civilians in a quarter-century prove true. But even Fabius stressed there was no question of sending in troops on the ground.
Britain, too, said no option should be ruled out "that might save innocent lives in Syria". But European forces can do little without U.S. help, and Washington shows little appetite for war.
Obama began a two-day bus trip to promote his domestic economic policies and made no comment on Syria. His spokesman said the tour showed he had "his priorities straight".
Syrian officials have called allegations against their forces "illogical and fabricated". They point to the timing of the attack, days after U.N. inspectors arrived after months of argument, and to previous assurances that, if they possessed chemical weapons, they would never use them against Syrians.
After months of negotiating with Assad's government to let inspectors into Syria, a U.N. team arrived in Damascus four days ago. Their task is to check on the presence, but not the sources, of chemical weapons that are alleged to have been released in three specific, small incidents several months ago.
Syria's government, which has accused the rebels of using chemical weapons in the past, offered no public response to calls for wider U.N. access.
"WE'RE BEING EXTERMINATED"
Many rebels and activists in the opposition area say they have lost interest in promises of U.N. investigations or in help from abroad: "We are 7 km away, just a 5-minute car ride from where they are staying," said activist Bara Abdelrahman.
"We're being exterminated with poison gas while they drink their coffee and sit inside their hotels."
Qassem Saadeddine, a commander and spokesman for the rebels' Supreme Military Council, said the group was still deliberating on how or if it should respond: "People are growing desperate as they watch another round of political statements and U.N. meetings without any hope of action," he told Reuters.
Syria's revolt against four decades of Assad family rule has turned into a brutal civil war that has killed more than 100,000 people in two and half years and divided the Middle East along largely sectarian lines. Among world powers the conflict has revived Cold War-era East-West tensions and on the ground the struggle has limped to a poisonous stalemate.
Western powers back the opposition but have been reluctant to fully commit to a revolt increasingly overtaken by Islamists linked to al Qaeda. Yet they have said the large-scale use of widely banned chemical weapons would be a game changer.
WORLD PAYING "LIP SERVICE"
Syria's southern neighbour Israel, still technically at war with Damascus, said it believed Syrian forces had used chemical weapons and accused the world of turning a blind eye: "The world condemns, the world investigates, the world pays lip service," Strategic Affairs Minister Yuval Steinitz said.
In Paris, Fabius said that if the Security Council could not make a decision, one would have to be taken "in other ways", but he did not elaborate.
Immediate international action is likely to be limited.
European officials speaking on condition of anonymity said that options ranging from air strikes, creating a no-fly zone, or providing heavy weapons to some rebels were all still on the table - but that there was little prospect of concrete measures without U.S. backing, which still seemed unlikely.
"The American reaction following yesterday's attack was cautious," said one. "And without U.S. firepower there's little we can do."
While France and Britain took a lead in attacking Muammar Gaddafi's forces to help Libya's revolt in 2011, the ultimately successful campaign against an enemy far weaker than Assad's military also relied heavily on U.S. firepower and logistics.
Assad's forces continued a heavy bombardment of the Ghouta region for a third day on Thursday, which activists say will further hinder U.N. investigators from entering the area.
FOAMING AT MOUTH
A spokesman from the opposition's Syrian National Coalition said bodies were still being found on the outskirts of Damascus.
"We expect the number to grow because we just discovered a neighbourhood in Zamalka where there are houses full of dead people," said Khaled Saleh, speaking in Istanbul.
Opposition activists said men, women and children were killed as they slept. They say several towns in Ghouta were hit with rockets loaded with poison gas before dawn.
Fahad Almasri, a spokesman for the Free Syrian Army in Paris, said local fighters had counted 29 separate projectiles fired from three military positions during Wednesday's pre-dawn attack, though not all appeared to have chemical warheads.
The firing from Qasioun mountain, Almezzah air base and a military compound in the suburb of Damascus hit targets across a swathe of towns and neighbourhoods northeast of the capital.
Syria is one of just a handful of countries that are not parties to the international treaty that bans chemical weapons, and Western nations believe it has caches of undeclared mustard gas, sarin and VX nerve agents.
Weapons experts said it was unclear from evidence so far what precise chemicals may have been involved and how they may have been delivered. While opposition groups spoke of rockets carrying gas canisters, analysts abroad said gases, possibly a cocktail of compounds, could have been released in other ways.
While Assad's armed forces are suspected of having such stocks, analysts also noted that rogue units, not under direct orders from the government might choose to use them - as might some opposition group, should it have captured such weapons.
(Additional reporting by Thomas Grove in Moscow, Domiic Evans in Beirut, Jeffrey Heller in Jerusalem, Anthony Deutsch in Amsterdam, Niklas Pollard in Stockholm, and Louis Charbonneau and Michelle Nichols in New York; Editing by Alastair Macdonald and Tim Dobbyn)