KABUL, Afghanistan – President Hamid Karzai has given up trying to talk to the Taliban, saying in a video released Saturday that Pakistan holds the only key to making peace with insurgents and must do more to support a political resolution to the war.

Karzai revealed his tougher stance against Pakistan, which he claims is harboring militants, on the same day that the Afghan intelligence service said it has hard evidence that former President Burhanuddin Rabbani’s assassination was planned on the southern outskirts of Quetta, the Pakistani city where key Taliban leaders are based.

Interior Minister Bismullah Khan Mohammadi went even further, stating in an Afghan parliamentary session that Pakistan’s Inter-Services Intelligence agency was involved in Rabbani’s killing — an allegation Pakistan has denied.

“Without any doubt, ISI is involved in this,” Mohammadi told Afghan lawmakers Saturday.

The claims follow similar accusations against Pakistan by the United States, reflecting the growing frustrations with a central player in the region whose cooperation is crucial even as its intentions are under question.

Critics have accused the Pakistani government of protecting Taliban leaders to maintain good relations with the group in anticipation of Western forces’ eventual withdrawal from the country — an allegation denied by Pakistan.

Many analysts also believe the ISI’s alleged support for insurgent groups is an attempt to promote Pakistan’s interests in Afghanistan and counter the influence of archenemy India, which Karzai plans to visit this week.

Addressing a public rally on Saturday, Pakistani Prime Minister Yusuf Raza Gilani offered to share intelligence on Rabbani’s assassination and said his nation was ready to hold talks with anyone interested in peace. Most of the Taliban leadership is thought to be living in Pakistan, and its governing council, the Quetta Shura, is named after the Pakistani city.

Calling Karzai his brother and friend, Gilani said, “He has some misunderstanding on the assassination of Professor Rabbani.”

“If any intelligence sharing or any cooperation is required, God willing, we will provide that,” Gilani said in his hometown of Multan, Pakistan. “We will help them, but they cannot doubt us.”

The Taliban have not claimed responsibility for killing Rabbani.

Lutifullah Mashal, a spokesman for the Afghan intelligence service, told reporters at a news conference that Rabbani’s killing was planned in an upscale residential area close to the center of Quetta called Satellite.

“The key person involved in the assassination of Rabbani has been arrested, and he has provided lots of strong evidence about where and how it was planned,” Mashal said. “We have given all that evidence to the Pakistan embassy.”

The Afghan intelligence documents handed over to Pakistan’s embassy in Kabul include the address, photographs and a layout of a house in Satellite, Mashal said. He said the Pakistanis also have been provided with the names of individuals who discussed Rabbani’s assassination at the house.

Karzai told a private television station in Kabul that Pakistan needs to act on the information.

“If Pakistan doesn’t help, then Afghanistan will go to international sources for an international investigation — to the United Nations. And this is Afghanistan’s right,” Karzai said in an interview broadcast Friday night on Noor TV.

The outgoing chairman of the U.S. Joint Chiefs of Staff, Adm. Mike Mullen, recently told the U.S. Senate Armed Services Committee that the Haqqani network, which is affiliated with the Taliban and al-Qaida, “acts as a veritable arm” of Pakistan’s intelligence agency.

Mullen accused the Haqqani network of staging an attack against the U.S. Embassy and NATO headquarters in Kabul and a truck bombing that wounded 77 American soldiers last month. He claimed Pakistan’s spy agency helped the group.