The United States called on its NATO allies on Thursday to provide more forces to provide security for Afghanistan's presidential election in August, but had only a limited response.

U.S. Defense Secretary Robert Gates said he would not seek a specific number of additional NATO troops from a meeting of NATO defence ministers in the Polish city of Krakow.

But he said Washington would like to see a short-term deployment of troops to Afghanistan from the alliance's rapid response force, the NRF, which has never been utilised.

"The message is that it is a new administration and (it) is prepared to make additional commitments to Afghanistan. But there clearly will be expectations that the allies must do more as well," Gates told reporters.

U.S. President Barack Obama authorised 17,000 more U.S. troops for Afghanistan this week, taking the U.S. contingent to around 55,000, in addition to the 30,000 from 40 other mostly NATO countries already operating in Afghanistan.

Some European allies have announced plans to send more troops, but these numbered in the hundreds, not thousands, and Germany said the NRF should not be used for Afghan duty.

"The NRF should not be used as a reserve," German Defence Minister Franz Josef Jung told reporters in Krakow. "The NRF has fundamentally different tasks."

U.S. officials have long been frustrated by European reluctance to make new long-term troop commitments to the Afghan mission and Gates said it was unlikely that large increases would be forthcoming anytime soon.

"WE REALLY NEED ADDITIONAL HELP"

But Gates said the Obama administration hoped NATO countries where the Afghan mission is politically unpopular could make significant new contributions to civilian development.

"We really need additional help on the civilian side ... frankly I hope it may be easier for our allies to do that than significant troop increases especially for the longer term."

Gates said more help was needed on governance and development, police training and funding of the Afghan army.

Italy said on Wednesday it would send 500 more troops by April and Germany publicly announced a pledge of 600 more soldiers it first made earlier in the year.

Britain, which has the second largest force in Afghanistan, said it had made no decision on whether to send more troops, but its Defence Secretary John Hutton said London felt it was up to other NATO countries to step up their commitments first.

Hutton hit out at the failure of allies to commit essential equipment to the Afghan operation.

"NATO has thousands of helicopters. We have only managed to put a very few in Afghanistan and that is an appalling indictment of NATO's inability to get behind very mission-critical operations," he said.

France reiterated it has no plans to send additional forces.

Bob Jackson of London's Chatham House think-tank said that if European allies failed to respond to U.S. calls, Washington would simply go it alone.

"In the lead-up to the Iraq war, some European leaders said they were not consulted properly. Do they want to be shut out of the process altogether? Europe will have opted out of the most important decision facing NATO since the end of the Cold War."