Zardari was in Paris on Monday for talks with French President Nicolas Sarkozy.

In a statement issued after the talks, Zardari's office said he told Sarkozy it was "unfortunate if some people continued to express doubts and misgivings about our will and determination to fight the militants to the finish."

"No other country in the international coalition has paid such a heavy price in this fight." The statement quoted him as saying.

'Double game'

Cameron's office insisted on Monday that the prime minister stood by his complaint, but made it clear that he was referring to elements with the Pakistani state and not to the policies of Zardari's government.

Senior political figures, including Pakistan's prime minister, voiced anger over the comments, which also led to protesters burning an effigy of Cameron in the streets of Karachi.

Pakistani military forces and civilians have born heavy losses in attacks by the Pakistani Taliban, especially in the two years since Zardari's wife, former prime minister Benazir Bhutto, was assassinated.

But many observers accuse Islamabad's ISI intelligence agency of playing a double game, cracking down on fighters within Pakistan while at the same time sponsoring the Afghan Taliban battling Nato forces in Afghanistan.