British Prime Minister Gordon Brown feels optimistic he can get NATO allies to send another 5,000 soldiers to Afghanistan.

Brown made his comments as U.S. President Barack Obama is under pressure to send 40,000 more troops to the war region in response to a request from NATO's top commander in Afghanistan, U.S. Gen. Stanley McChrystal.

McChrystal says the mission needs an extra 40,000 troops to bolster the 71,000 already there, amid growing Taliban insurgency and casualties.

During an interview with the BBC Friday, Brown said he thought he could get some of the 43 other nations involved in the International Security Assistance Force to step up to help share the burden.

"I think we can probably get another 5,000 forces into Afghanistan... and Britain will be part of that," he said.

"I have taken the responsibility of asking others in Europe, and outside Europe actually, if they will back this strategy which is partnering the Afghan forces, mentoring the Afghan forces," he said.

Among those outside Europe would be Canada, which already has 2,800 soldiers in Afghanistan. But the Harper government has said we will halt our combat role there in 2011.

Finland and the Netherlands, too, have either pulled troops out or set withdrawal dates.

Other countries, such as Denmark, Italy, Norway and Sweden, say they will maintain current troop levels but have no immediate plans to increase them, cognizant of public demands for a speedy exit.

Only Britain and Turkey have made significant pledges, and Turkey has committed non-combat personnel only.

With 9,000 troops in the country, Britain is the second largest contributor to the international coalition. But the war is increasingly unpopular in the U.K.

Some 232 British soldiers have died in Afghanistan since 2001. Families and military commanders have blamed deaths on a lack of equipment, and there has been growing criticism that Brown has failed to show tangible benefits of the mission.

In his interview, Brown launched an impassioned defence of the controversial military campaign, acknowledging that Britain needed to "adjust our approach" amid rising casualties.

The U.S.'s Obama is also grappling with sending more U.S. troops to Afghanistan. While on a mission to Asia Friday, the president stopped at Elmendorf Air Force Base in Alaska and told a military audience he will commit more forces to Afghanistan only if necessary and if it receives public support.

"I will not risk your lives unless it is necessary to America's vital interests," Obama told the troops.

"And if it is necessary," Obama added, "the United States of America will have your back. We'll give you the strategy and the clear mission you deserve. We'll give you the equipment and support you need to get the job done. And that includes public support back home."

Meanwhile, Germany announced Friday it would send more than 100 extra troops to Afghanistan in January, even though support in Germany for the war is low.

Defence Minister Karl-Theodor zu Guttenberg said during a visit to his country's troops in Afghanistan that soldiers would be deployed in the northern province of Kunduz, where most of Germany's 4,365 troops are stationed.

With reports from the Associated Press