Former US Ambassador to Afghanistan Zalmay Khalilzad said Pakistan has always used the Taliban and Haqqani Network in its foreign policy and that it gives refuge to extremist groups.

Speaking to TOLOnews, Khalilzad said Pakistani generals sat beside leaders of insurgent groups at the first round of peace talks. The American politician said the Afghan government has had a number of problems over the last year and that it has had to work hard to gain public trust.

"This shows the lack of a system and a work plan in the government. We hope that lessons are learned from mistakes made in Kunduz war and that the mistakes are not repeated," he said.

"No doubt, without the help of Pakistan, the [terrorist] groups would not have the ability to operate in Afghanistan in ways that they are doing now and they would not have been able to threaten Afghanistan as much as they do," Khalilzad said.

"Pakistan is the center or capital of the groups – whether they are Taliban or Haqqani. There is no doubt that Pakistani generals were present at the [the peace talks] session which was held with the Taliban and Haqqani network leaders."

He went on to say: "Regarding Daesh, it is clear which country is mostly supporting the group and on the part of Taliban and Haqqani Network we can say surely that Pakistan is their [Taliban's] supporter."

Khalilzad stressed the need to establish transparency in the government and said U.S President Barak Obama's new strategy has created more optimism in winning the war on terror in Afghanistan.

He said the presence of 10,000 US troops in Afghanistan can accelerate the training and equipment process of Afghan security forces.

Khalilzad, who was born in Afghanistan, was U.S envoy to Kabul but is currently a counselor at the Center for Strategic and International Studies (CSIS) and president of Khalilzad Associates, an international business consulting firm based in Washington, DC.

He was the United States Ambassador to the United Nations under President George W. Bush and has been involved with U.S policy makers at the White House, State Department and Pentagon since the mid-1980s.