Afghan President Hamid Karzai said Pakistan is essentially using the Taliban to fight a proxy war in his country. (SHAH MARAI/AFP/GETTY IMAGES)

Afghan President Hamid Karzai escalated his criticism of Pakistan on Monday night, charging in a speech that the country is not a sincere partner for peace and is essentially using the Taliban to fight a proxy war in his country.

“Pakistan has pursued a double game toward Afghanistan, and using terrorism as a means continues,” Karzai said in an address from the presidential palace.

Such sentiments are common among Afghans, but Karzai and other senior members of his government have grown increasingly blunt in their accusations. Karzai has staked out a new position in recent remarks, saying that peace talks with the Taliban are futile unless they involve the Pakistani authorities who he argues exert control over the insurgents. Pakistan denies such involvement with the Taliban.

Karzai in recent years has called the Taliban “brothers” and regularly encouraged the insurgents to reconcile with the Afghan government. But after a string of political assassinations and attacks in Kabul, he has taken a more belligerent line.

“Seeking one-sided peace will not bring peace,” he said Monday before a scheduled trip to India, Pakistan’s historical enemy. “Therefore, the government of Afghanistan has the responsibility to decisively fight against the enemies of independence and peace in Afghanistan.”

The acrimony between the neighbors has risen to new heights since the killing last month of former Afghan president Burhanuddin Rabbani, the government’s chief peace envoy, by a Taliban emissary who visited Rabbani under the guise of seeking negotiations. Afghan officials said that the assassination was plotted in the Pakistani city of Quetta and that Pakistan’s intelligence agency was involved.

Over the weekend, Pakistan rejected those claims, calling them “baseless allegations.” The Pakistani Foreign Ministry said in a statement Sunday that the alleged mastermind was an Afghan who had been “roaming around in Kandahar and Kabul for quite some time.”

“Instead of making such irresponsible statements, those in positions of authority in Kabul should seriously deliberate as to why all those Afghans who are favorably disposed towards peace and towards Pakistan are systematically being removed from the scene and killed,” the statement said. “There is a need to take stock of the direction taken by Afghan intelligence and security agencies.”

The leader of a Taliban-allied insurgent group blamed for many attacks in Kabul, and accused by U.S. officials of working with Pakistan’s intelligence agency, also denied that his group was involved in Rabbani’s killing. Sirajuddin Haqqani, whose father leads the group known as the Haqqani network, told the BBC that the group is not supported by Pakistani intelligence.

He also said his group has been approached by U.S. foreign intelligence officials as well as officials from other countries “asking us to leave the sacred jihad and take an important part in the current government.”

“We know that their aim is not peace,” he added. “They want to create tension among” the insurgent groups.

Special correspondent Sayed Salahuddin contributed to this report.