Afghan President Hamid Karzai pressed Pakistan on Wednesday to help his country negotiate with the Taliban, despite a series of high-profile assassinations and attacks that have diminished peace prospects and intensified suspicions that Islamabad supports and shelters the militants.

Karzai's appeal came in Istanbul during a one-day conference on Afghanistan that drew regional players as well as Western powers. While a successful show of solidarity, the gathering also underscored how much is left to do in Afghanistan as international combat forces prepare to leave by the end of 2014.

Karzai said a peace process cannot succeed without the participation of the top leadership of the Taliban, which he alleged was based in Pakistan.

"Our hope is that, with help from our brothers in Pakistan, we will manage to wean away the Taliban leadership from some of the long-established networks of support they enjoy outside Afghanistan and integrate them into the peace process," the Afghan leader said.

Pakistan denies that the Afghan Taliban's top leaders are based on its territory. It has bristled at U.S. and Afghan accusations it plays a double game, fighting some militant groups while supporting others it views as potential useful proxies in future conflicts with archrival India.

But the Sept. 20 assassination of Burhanuddin Rabbani, a former president and leader of the Afghan High Peace Council, as well as other high-profile attacks in Afghanistan _ some ascribed to the Haqqani network, a militant group with bases in Pakistan _ have added to concerns about Islamabad's loyalties.

On Tuesday, Karzai and his Pakistani counterpart, Asif Ali Zardari, discussed a joint inquiry into Rabbani's killing. But since the Pakistani army has far more sway over foreign policy than Zardari's weak government, it's unclear how much the Pakistan president can accomplish.

In a statement, the Afghan High Peace Council said it was continuing work to open negotiations with the Taliban, but would not talk to anyone whose identity could not be verified or who appeared to be pushing the political goals of other countries.

"It is time that our neighboring countries stop their interference, and rather than increasing violence in Afghanistan, allow the Afghan people to live in peace and prosperity," the council said.

In an opulent hall on the shores of the Bosporus Strait, delegates delivered speeches promising support for Afghan sovereignty, and endorsed a transition to Afghan security leadership, efforts for a political solution to the war and economic development.

China, India and Iran sent envoys at the conference. The U.S. and other countries with troops in Afghanistan also sent representatives.

"The terrorism, extremism, as well as drugs and human trafficking that Afghanistan is struggling against are not problems that one country can deal with on its own," Turkish President Abdullah Gul said.

U.S. Deputy Secretary of State William Burns cited an Oct. 29 suicide truck bombing in Kabul that killed 17 people, including a number of Americans, as an example of U.S. sacrifice in Afghanistan. He said regional powers had often acted "in ways that make things worse," instead of cooperating to solve problems.

Rhetoric alone was not enough to achieve stability, he added.

"It doesn't have to be this way," Burns said. "While outsiders cannot impose a solution, we should facilitate contact and provide support."

Afghan officials were seeking regional support for the idea of a "New Silk Road," an integrated trade and transportation network that would run through Afghanistan. The nation was at the crossroads of the historic east-west trade route known as the Silk Road.

The U.S. has also pushed economic cooperation as a way to wean Afghanistan off international assistance and undercut the appeal of extremism.

Amnesty International said Afghanistan should work with its neighbors to protect human rights in the run-up to NATO's withdrawal and afterward.

Sam Zarifi, Asia-Pacific program director for the group, said progress had been made since the U.S.-led invasion that toppled the Taliban in 2001, citing a decrease in discrimination against women and better access to education and health care.

But advances have faltered in justice and policing, and in improving conditions for some 450,000 people displaced by the conflict, Zarifi said.