The United States has accused Pakistan’s main spy agency of deliberately undermining Nato efforts in Afghanistan by helping the Taliban and al-Qaeda militants they are supposed to be fighting, the Sunday Times reported.

President George W Bush confronted Yusuf Raza Gilani in Washington last week with evidence of involvement by the ISI in a deadly attack on the Afghan capital and warned of retaliation if it continues.

The move comes amid growing fears that Pakistanís tribal areas are turning into a global launch pad for terrorists. Gilani, on his first official US visit since being elected in February, was left in no doubt that the Bush administration had lost patience with the ISIs alleged double game. Bush warned that if one more attack in Afghanistan or elsewhere were traced back to Pakistan, he would have to take serious action.

An intercepted telephone conversation apparently revealed that ISI agents masterminded the operation. The United States also claimed to have arrested an ISI officer inside Afghanistan. Pakistani ministers said they had left Washington reeling from what they described as a grilling and shocked at the trust deficit between Pakistan and its most important backer.