Afghan President Hamid Karzai has said he is suspending efforts to hold peace talks with the Afghan Taliban and will focus instead on dialogue with neighbouring Pakistan. He said he had made the decision after the killing of the former Afghan president Burhanuddin Rabbani by a suicide bomber purporting to be a Taliban peace emissary. Speaking in Kabul, Mr Karzai told a group of religious leaders that there were no partners for dialogue among the Taliban and it was not possible to find the Taliban leader, Mullah Omar. Meanwhile, the United States has said that attempts to set a fresh course with Pakistan are being hobbled by bad options and bureaucratic tensions. In the wake of a blunt and public accusation by the top US military officer that Pakistani intelligence supported a militant attack on the US Embassy in Kabul, officials at the Pentagon, State Department and White House are urgently debating an array of unattractive choices. Washington desperately wants to tighten the screws on the Haqqani network, a militant group US officials say was supported by Pakistan's powerful ISI intelligence agency in the embassy attack and in other violence that threatens a smooth US withdrawal from Afghanistan. Despite mounting exasperation in Washington, dramatic change in US policy looks unlikely in the short term toward Pakistan. "I don't see that we have a comprehensive new strategy on Pakistan in the works," said Bruce Riedel, a former CIA official who advised the highest levels of the Obama administration on regional policy. "I think we need one, or at least we need to reshape the one we have."