KABUL, Afghanistan -- Afghan President Hamid Karzai said Saturday that the recent assassination attempt on the country's intelligence chief was planned in Pakistan, but vowed it would not stop him from seeking Islamabad's help in coaxing militants to the negotiating table.

The attack, carried out by a suicide bomber posing as a peace messenger, severely wounded Asadullah Khalid, dealing a setback to fragile efforts to reconcile with the Taliban and find a political resolution to the war in Afghanistan, now in its 12th year.

Karzai did not provide any evidence to back up his claim that the attack on Khalid was organized in Pakistan, and he was careful not to accuse Islamabad of having any role in Thursday's suicide blast. But he stressed that he would raise the issue with high-ranking Pakistani officials.

"We will be seeking a lot of clarifications from Pakistan because we know that this man who came there in the name of a guest to meet with Asudullah Khalid came from Pakistan," Karzai said. "We know that for a fact."

Karzai said Khalid, the head of the National Directorate of Security, was recovering from wounds to his torso and lower body after the bomber detonated explosives that he had hidden inside his body. The Afghan intelligence agency said earlier that the explosives were hidden in the bomber's underwear.

Karzai described the attack as "a very sophisticated and complicated act by a professional intelligence service."

"Where is this intelligence service? Is it in our neighbourhood, or somewhere else? We need to find out," he said.

The Taliban has claimed responsibility for the attack on Khalid -- the fifth attempt on his life in as many years.

The blast was reminiscent of the September 2011 assassination of former Afghan President Burhanuddin Rabbani, who at the time was the leader of a government-appointed peace council. In that attack, an insurgent posing as a Taliban peace envoy detonated a bomb hidden in his turban as he met Rabbani at his Kabul home. Afghan officials have said that the Rabbani killing was planned in the Pakistani city of Quetta.

Pakistan is seen as a key player in the Afghan peace process. Islamabad has ties to the Taliban that date back to the 1990s, and many of the group's leaders are believed to be detained or living on Pakistani territory.

Despite his claims that the attack was planned in Pakistan, Karzai said it would not deter him from pursuing dialogue with Pakistan on the peace process, and he reiterated his request for Islamabad to release Afghan Taliban figures who have expressed an interest in reconciliation with his government.

Karzai said it was the third attack on key Afghan figures that came after his government appeared to be gaining traction on peace efforts.

In July 2011, Karzai's half-brother, Ahmed Wali Karzai, was gunned down by a close associate in Kandahar, the largest Afghan city in the south.

Karzai said progress also was being made around the time that Rabbani was killed, and the attack on Khalid came just a few weeks after Pakistan agreed to release at least nine Taliban prisoners at the request of the Afghan government to help jumpstart the peace process.

The decision to release the Taliban prisoners was the most encouraging sign yet that Islamabad is willing to play a constructive role in peace efforts that have made little headway since they began some four years ago.

Karzai said he knows that some Afghans will blame Pakistan for the latest attack, but he cautioned his countrymen, saying "it is not right to point a finger at Pakistan" and that "we need to be very careful and find the reality and facts."

Pakistan helped the Taliban seize control of Afghanistan in the 1990s, providing funding, weapons and intelligence, and the Afghan government and the U.S. have accused Islamabad of continuing to support the group. Pakistan has denied the allegations, but many analysts believe the country continues to see the Taliban as an important ally in Afghanistan to counter archenemy India.

The U.S. and its allies fighting in Afghanistan are pushing to strike a peace deal with the Taliban as international combat troops wind down their campaign by the end of 2014. But obstacles remain, and it is unclear whether the Taliban even intend to take part in the process, rather than just wait until foreign forces withdraw.

With the 2014 deadline looming and security in the country still elusive, the U.S. and Afghanistan are negotiating a bilateral security agreement will set up a legal framework needed to continue to operate American forces in Afghanistan after that date.

Karzai said Kabul would be willing to consider giving immunity to U.S. troops who stay past 2014, but not until the U.S. guarantees respect for Afghanistan's sovereignty.

"But before I do that, I must make sure that the United States of America respects Afghan sovereignty, that it does not take prisoners in Afghanistan, that it does not keep prisons in Afghanistan in violation of the agreements with us, that it does not violate Afghan homes, (and) that there is no bombardment of Afghan villages and homes," he said.

In other developments, two civilians were killed when a roadside mine exploded Saturday in Bak district of eastern Khost province. The provincial governor's office said five other civilians and four Afghan soldiers were wounded in the mid-day blast that occurred during the soldiers' foot patrol.