General David Petraeus, the new commander of US and Nato forces in Afghanistan, yesterday called for unity in the civilian and military effort to turn back the Taliban, saying, "In this important endeavour, cooperation is not optional."

In his first public comments since he arrived to assume command of the international military mission in Afghanistan, Petraeus said he would work to improve co-ordination between troops on the battlefield and civilians trying to bolster the Afghan government and improve the lives of the people.

His predecessor, General Stanley McChrystal, was fired last month for intemperate remarks that he and his aides made to Rolling Stone magazine about Obama administration officials.

"Civilian and military, Afghanistan and international, we are part of one team with one mission," Petraeus told about 1,700 invited guests at the US embassy for a pre-4 July celebration marking American independence.

Petraeus, widely credited with turning around the US war effort in Iraq, is taking over the 130,000-member Nato-led international force at a time of rising violence and growing doubts in Washington and other allied capitals about the effectiveness of the counterinsurgency strategy, which Petraeus pioneered.