Munich  - NATO and Afghan leaders were set to debate the future of the international mission in Afghanistan on Sunday amid tensions between Washington, Kabul and European capitals.

US National Security Advisor James Jones, Afghan President Hamid Karzai and German Defence Minister Franz-Josef Jung were to address the prestigious Munich Security Conference at a time when Western leaders are becoming increasingly critical of Karzai's regime and NATO members are struggling to raise troops to combat the Taliban.

NATO has sent some 55,000 troops to the UN-mandated International Security Assistance Force (ISAF) in Afghanistan, almost half of them from the United States.

But the alliance is fighting an increasingly bitter battle against the resurgent Taliban, with commanders on the ground calling out for more soldiers.

US President Barack Obama has pledged to almost double the number of US troops in Afghanistan, but has called on European members to boost their efforts in the country, either by sending more men or by providing more support to the Afghan government, army and police.

"America will do more. The bad news is that America will ask more from our partners as well," US Vice-President Joe Biden told the conference on Saturday.

That call is likely to cause anxiety in Europe, where the Afghan campaign is far from popular with voters, and where some governments are reluctant to commit soldiers to the hottest combat areas, despite fierce pressure from allies such as Britain and Canada.

It will be a particularly sensitive issue in Germany, which faces federal elections in September. NATO officials say that they are keen to avoid the Afghan mission becoming an electoral issue.

At the same time, Western capitals have become increasingly vocal in their criticism of Karzai's government, which they accuse of inefficiency, corruption and stalling key reforms.

In return, Karzai has demanded that NATO do more to prevent civilian casualties in his country.

Obama has also pledged to widen US efforts in the region to take in Pakistan - frequently portrayed as a safe haven for militants.

Later on Sunday, Pakistan's Foreign Minister Makhdoom Qureshi is set to debate the future of NATO's Afghan mission with, among others, British Defence Minister John Hutton and US General David Petraeus, who scored some of the earliest successes in stabilizing Iraq.

Richard Holbrooke, Obama's special representative for Afghanistan and Pakistan, is also due to join the debate. dpa