KABUL (Reuters) - Afghanistan security forces have detained five insurgents with massive quantities of explosive materials intended for use in attacks on crowded areas of Kabul and linked them to Pakistan-based militants, an intelligence spokesman said on Saturday.
The alleged connection to militants in Pakistan will likely step up the pressure on Islamabad, after a recent coordinated assault by insurgents on diplomatic and government areas in Kabul and elsewhere put the spotlight on the South Asian nation.
"It could have caused large-scale bloodshed," National Directorate of Security (NDS) spokesman Shafiqullah Tahiri told a news conference.
"Three Pakistani terrorists and two of their Afghan collaborators who placed the explosives under bags of potatoes in a truck were caught."
The 10 tons (22,046 lbs) of potassium, used to make bombs, were stuffed into 400 bags and hidden under potatoes in the back of a Pakistan-registered truck on Kabul's outskirts, Tahiri said.
The material was loaded at a storage facility in upmarket Hayatabad, situated on the ring road near Peshawar, and trucked across the border, the NDS said.
The U.S. ambassador to Afghanistan, Ryan Crocker, said there was "no question" that the Haqqani network, which Washington believes is based in Pakistan's North Waziristan region, mounted last weekend's 18-hour rocket and gunfire operation in Kabul.
Crocker called on Pakistan to crack down on the Haqqanis and said the response to that demand would influence future ties between the strategic allies.
Relations have been heavily strained by a series of events, including the unilateral U.S. special forces raid that killed Osama bin Laden on Pakistani soil last May.
Pakistan has denied accusations that its military spy agency sees the Haqqanis as a counterweight to the growing influence of rival India in Afghanistan.
Tahiri said the five men confessed to receiving training from Noor Afzal and Mohammad Omar, who he identified as key commanders of the Pakistani Taliban and Pakistan intelligence.
Video footage released by NDS to media showed the detained men, including the alleged Pakistanis, talking about where they came from while sitting against a blank white wall.
A Pakistani intelligence official declined comment on the accusations, while Afghan officials were not immediately available to give additional information.
While the Pakistani Taliban cooperate with the Afghan Taliban, they are sworn enemies of the U.S.-backed Islamabad government and have mounted suicide bombings against Pakistani intelligence officials and security forces.
It's still not clear whether the confessions will create a new crisis in relations between Pakistan and Afghanistan.
Relations went into a freeze last year after Kabul accused Pakistani agents of playing a role in the September assassination of the head of the country's High Peace Council.
Afghanistan has long been suspicious of Pakistani intentions, accusing Islamabad of backing insurgent groups to further its interests.
Pakistan's government denies supporting or giving sanctuary to insurgents on its territory and has said it would do what it can to advance the Afghan reconciliation process.
Afghan officials say privately that Pakistan has not delivered on its promises, despite upbeat official assessments of cooperation from both sides in recent months.
The Taliban in March said they were suspending peace talks with the United States and a plan to open an office in the Gulf state of Qatar to smooth negotiations, accusing Washington of double-dealing over confidence-building measures including the release of insurgents from a U.S. military prison in Cuba.
Reporting by Hamid Shalizi, Writing by Michael Georgy and Rob Taylor; Editing by Sanjeev Miglani