(CNN) -- Afghan President Hamid Karzai dismissed calls for negotiations with the Taliban, saying neighboring Pakistan is the key to peace talks with the insurgency, the presidential press service said in a statement Saturday.
"The people of Afghanistan say 'president, you have called for peace but peace with who?'" according to the statement. "I don't have another answer for them, except to say that it is Pakistan we have to approach. We cannot find Mullah Omar. Where is he? We don't know where the Taliban Shura is."
The comments came the same day Afghanistan's intelligence service said it provided evidence that the assassination of former Afghan President Berhanuddin Rabbani was planned by the Taliban council in Quetta, Pakistan.
Rabbani, who was spearheading the reconciliation process with the Taliban, was killed in a suicide bomb attack at his home on September 20. Police said the bomber claimed to be a Taliban member who had come for the talks about peace and reconciliation and detonated the explosives as he entered the home.
"We have given the evidence to the Pakistan Embassy in Afghanistan to cooperate with us," Lutfullah Mashal, Afghanistan's intelligence service spokesman, told reporters.
"We have concrete evidence that (Taliban council in Quetta) was responsible for killing the head of the peace council."
Among the evidence turned over to Pakistani officials were photographs, documents, maps and the location where Rabbani's killing was planned, Mashal said.
Long an enemy of the Taliban, Rabbani was a controversial choice when appointed by Karzai as chairman of the High Peace Council a year ago. He was forced to flee Kabul when the Taliban took over in 1996, but he continued to lead resistance to the regime from his stronghold in Faizabad in northern Afghanistan.
Rabbani's death shocked the war-torn country, undermined the fledgling peace initiative and stoked fears of renewed ethnic conflict between Pashtuns and others, such as Rabbani's ethnic group of Tajiks.
Karzai believes any negotiations must be conducted with Pakistan since the enemy "sanctuaries and operating places" are there, the statement said.
In the statement, Karzai condemned insurgent attacks launched from Pakistan's volatile tribal area that borders Afghanistan.
"We also condemn the attacks on Nuristan and Kunar from Pakistan, and have asked the Foreign Ministry to use emergency diplomacy and contacts to stop these attacks," the statement said.
The comments by the Afghan president follow ones made by U.S. Joint Chiefs of Staff Chairman Adm. Mike Mullen, who said last week that the Haqqani network -- which has carried out a number of high profile terror attacks in Afghanistan -- acted "as a veritable arm of Pakistan's intelligence."
Pakistan's prime minister has rejected Mullen's accusations.
Western counterterrorism officials believe that contrary to Pakistan's assertions, the Haqqanis rely on Pakistani territory -- specifically the tribal areas of North Waziristan and the Khurram agency -- to organize, resupply and raise funds.
CNN's Nick Paton Walsh, Matiullah Mati and Ruhullah Khapalwak contributed to this report.