RIYADH (Reuters) - Gulf states traded public barbs on Saturday, showing little sign of resolving the region's deepest rift in years, five days after Arab nations severed diplomatic, trade and transport ties with the tiny Gulf kingdom of Qatar.
Foreign leaders expressed growing concern over the dispute, which pits Qatar against Saudi Arabia, the United Arab Emirates (UAE), Bahrain and Egypt. With backing from U.S. President Donald Trump, they accuse Qatar of supporting their regional arch-rival Iran as well as Islamist militants.
Kuwait has led a regional effort to mediate, but the four states intensified the pressure on Friday by placing dozens of people with alleged links to Qatar on terrorism blacklists.
A senior UAE official followed on Saturday by calling Qatar "duplicitous", alleging in a series of tweets that its funding of militants had sown chaos and violence throughout the region.
"Qatar has been riding (the) tiger of extremism & terrorism. Cost to region & world too high," tweeted Anwar Gargash, the UAE minister of state for foreign affairs.
"Diplomacy only way forward. Process can only work following clear indication that Qatar will stop support & finance of extremism & terrorism."
Qatar's foreign minister fired back that there was "no clarity" in such accusations, speaking in an interview with RT Arabic in Moscow after emerging from talks with Russian Foreign Minister Sergei Lavrov.
"Qatar is accused of having a hidden relationship with Iran, but its relations with Iran are clear, transparent and time-tested," said Sheikh Mohammed bin Abdulrahman al-Thani, noting that the UAE does more trade with Iran than Qatar does.
He denied that Qatar supported Egypt's outlawed Islamist movement, the Muslim Brotherhood, and Hamas, the Palestinian Islamist group that controls the Gaza Strip. He dismissed as "fantasy" a Saudi media report that he had met in Baghdad with the head of Iran's Quds Force, controlled by Iran's powerful Revolutionary Guards.
He said Qatar remained committed to a Kuwaiti-led mediation effort, but that he had yet to receive a clear list of demands.
As conciliation efforts in the Gulf appeared to stall, leaders in Russia, Turkey, Germany and the United States expressed increasing concern.
After German Chancellor Angela Merkel called the situation "very unsettling" on Friday, her foreign minister, Sigmar Gabriel, cautioned on Saturday that it could lead to war.
Russian Foreign Minister Sergei Lavrov told Sheikh al-Thani of Moscow's concern and called for talks.
And Turkish President Tayyip Erdogan - who has pledged food and troops to Qatar in the face of a blockade from its neighbours - hosted Bahrain's foreign minister and urged that the dispute be resolved by the end of the holy month of Ramadan.
However, mixed messages from U.S. officials appeared to complicate the diplomacy, as Gulf media cited selectively from divergent statements to bolster their positions.
Saudi Arabia and Bahrain issued statements welcoming U.S. President Donald Trump's demand the previous day for Qatar to stop supporting terrorism, while ignoring a U.S. State Department call for them to ease pressure.
Saudi Arabia said it was committed to "decisive and swift action to cut off all funding sources for terrorism" in a statement carried by the state news agency SPA, while Bahrain hailed U.S. efforts to ensure "international solidarity" on the issue.
The United Arab Emirates praised Trump's "leadership in challenging Qatar's troubling support for extremism" in a separate statement released on Friday.
Trump had accused Qatar of being a "high level" funder of terrorism on Friday, even as the Pentagon and U.S. Secretary of State Rex Tillerson cautioned against the military, commercial and humanitarian effects of a blockade imposed by Arab states and others.
A separate SPA report on Saturday acknowledged Tillerson's call for Qatar to curtail support for terrorism, without mentioning that he had also said the crisis was hurting ordinary Qataris, impairing business and harming the U.S. fight against the Islamic State militant group.
Saudi Arabia said its action followed the conclusions of last month's Arab Islamic American Summit in Riyadh, where Trump delivered a speech about Islamist extremism.
Trump said he had helped to plan the move against Qatar, although a senior administration official told Reuters this week that Washington had had no indication from the Saudis or Emiratis during the visit that they would sever ties with Qatar.
On Saturday, Niger announced it had recalled its ambassador to Qatar in solidarity with Arab countries.
Additional reporting by Mostafa Hashem; Editing by Kevin Liffey