A NATO spokesman admitted that strains remain among alliance members, notably over plans for closer cooperation between ISAF's peacekeeping mission and the US-led Operation Enduring Freedom (OEF), which tackles more frontline combat operations.

"All nations agree that ISAF and OEF need to work more closely together, and that when NATO takes over operations throughout the country that there must be unity of command," said NATO spokesman James Appathurai.

But he said: "Within that is where the details need to be worked out, adding: "Different countries have different visions."

Rumsfeld, who is discussing plans for expanding the NATO-led force in Afghanistan over the next year into more volatile southern parts of the country, urged allies on Tuesday not to hobble NATO commanders in places like Afghanistan and Kosovo by putting national restrictions on the use of their forces.

"One of the issues we'll have to wrestle with is the reality that while a number of NATO nations been reducing the restrictions that they impose on their forces ... some nations have not yet done that," he said.

Complaints about caveats

Although he identified no country by name, Rumsfeld alluded to an incident last year in Kosovo in which German NATO troops failed to respond to a serious outbreak of ethnic unrest because of their national rules of engagement.

He complained that so-called national caveats -- restrictions that governments place on the use of their forces in NATO missions -- are so numerous it takes 17 pages to list them all.

NATO has beefed up its troop levels in the run-up to Afghanistan's first parliamentary elections in three decades next weekend, which has seen a surge in violence across the country.

Britain, Canada and the Netherlands are to lead the move into the south, joining some 18,000 US soldiers who have long been fighting al Qaeda and Taliban fighters, in particular along the eastern border with Pakistan.

German opposition

German Defense Minister Peter Struck, hosting the Berlin talks, stressed his country's opposition to a merger the two missions Tuesday.

"

I don't want our soldiers to face further dangers if these two mandates are linked to each other," he told RBB radio in Berlin

Rumsfeld also said the US wants NATO to develop new roles as well as straight peacekeeping "It would be nice if NATO developed counter terrorism capabilities .. which don't exist at the present time as a NATO function," he said.

New strategy needed

At the same time Afghan President Hamid Karzai urged the US and other world leaders to reconsider the strategy for fighting terrorism in the war-torn country, saying there should be a focus on the "sources of terrorism."

"We and the international community, the coalition, must sit down and reconsider and re-think whether the approach to the threat of terrorism that has (been) taken is the absolutely right one," he told the BBC.

The NATO spokesman noted next weekend's elections mark a key point in Afghanistan, as it draws to the end of a framework set out by world leaders after the oust of the Taliban following the September 11, 2001 terror attacks.

"We need a .. new road map for how the international community can work together in support of the Afghan government," he said, while stressing that no formal decisions were expected at the Berlin talks.