Afghan President Hamid Karzai has ruled out further talks with the Taliban, saying “we cannot keep talking to suicide bombers.”

After a summit meeting Tuesday with his Pakistani counterpart, Asif Ali Zardari, and Turkish President Abdullah Gul, in the Turkish city of Istanbul, Mr. Karzai said his government would instead continue to talk with Pakistan about finding solutions to the insurgency-related violence.

Afghan and U.S. officials say Pakistan can play a crucial role in the Afghan-led reconciliation process with insurgents.

Mr. Gul, who hosted the summit, said Pakistan agreed to cooperate with Afghanistan on a joint inquiry into the September 20 assassination of Afghanistan's top peace negotiator, former President Burhanuddin Rabbani, which halted the reconciliation process. He said the three sides established a cooperation mechanism that will hopefully produce results.

Afghan officials accused Pakistan's military spy agency of involvement in the attack, a charge Pakistan strongly denies.

The meeting between the presidents of Afghanistan and Pakistan was the first since Rabbani's death and came a day before foreign ministers from 14 countries, including France, Germany and India, gather for a key regional conference.

The gathering will focus on Afghan efforts for a political solution to the decade-long conflict and security and economic development in Afghanistan as foreign combat troops reduce their presence in the country and leave by the end of 2014.

U.S. Secretary of State Hillary Clinton was set to take part in the conference, but cancelled her visit to Istanbul because of the death of her mother.

Afghan and Pakistan military leaders have also been meeting in Istanbul, and the two nations were expected to sign a security cooperation agreement.