David Cameron and Liam Fox welcome General David Petraeus's appointment to lead the international forces in Afghanistan

On the back of his comments to Rolling Stone magazine, General McChrystal resigned earlier this evening as commander of the Nato-led International Security Assistance Force in Afghanistan.

President Obama has announced that General David Petraeus will take over as soon as the Senate confirms his position, with the British Deputy Commander of ISAF, Lt Gen Nick Parker, assuming command in the interim.

A statement from a Downing Street spokesman was releaseing saying that Petraeus was "the right man" to take command:

"The Prime Minister has spoken to General Parker this evening. The Prime Minister told the President of General Parker's determination that the mission in Afghanistan 'would not miss a beat' during this period. The Prime Minister is grateful to General McChrystal for his service in Afghanistan as the Commander of ISAF and his contribution to the campaign, notably through his role in defining and taking forward the current counter-insurgency strategy. The British Government's resolve to support our brave servicemen and women and make progress in this crucial year is undiminished. It is vital for our national security that Afghanistan should never again be a safe haven for Al Qaeda".

Defence Secretary Liam Fox added that said General Petraeus was an "outstanding general who will lead ISAF I think with distinction":

"We will get continuity as we must have in this extremely difficult struggle... I think Gen McChrystal contributed a great amount personally.. General Petraeus is enormously distinguished as we know and will continue with that strategy."

Jonathan Isaby