Sibghatullah Mujaddedi, who is also head of the upper house of the Afghan Parliament, said he suffered burns to his hands and face from the blast, when a station wagon exploded close to his vehicle on a Kabul street.
He accused Pakistan's Inter-Services Intelligence agency of trying to kill him. He said that Afghanistan had information that six people had entered the country to assassinate him, but did not offer any proof.
"We have got information that ISI of Pakistan has launched a plan to kill me," Mujaddedi told a news conference hours after the attack, which police said killed the two attackers and two bystanders.
"What is my fault? My fault is that I am working for the peace and prosperity of Afghanistan," he said. "(President Gen. Pervez) Musharraf and ISI of Pakistan do not want Afghanistan to be safe and secure."
Islamabad dismissed Mujaddedi's charges.
"Pakistan rejects the baseless allegations," Pakistan's Foreign Ministry spokeswoman Tasnim Aslam said.
There was no immediate claim of responsibility for the bombing, the latest in a stream of suicide attacks that mark a disturbing change in tactics for Taliban-led militants fighting the government of President Hamid Karzai and U.S.-led coalition and NATO forces in Afghanistan.
Mujaddedi's allegation of a Pakistani plot will enflame a row that broke earlier this month after Kabul revealed it had shared intelligence with Islamabad that Taliban leader Mullah Omar was hiding in Pakistan and terrorist training camps on its soil were churning out suicide attackers. Pakistan dismissed the intelligence as outdated and strongly criticized Afghanistan for publicizing it.
Pakistani intelligence agencies helped create the Taliban militia, but Islamabad renounced its ties with the hardline regime in late 2001 just before the U.S. launched an attack to oust the Taliban from power in Afghanistan for hosting al Qaeda leaders who plotted the Sept. 11 attacks.