British and U.S. officials urged other NATO members Tuesday to send more troops to Afghanistan, saying the alliance''s success there required a more equal sharing of the war burden.

For months NATO has called for boosting its 50,000-troop mission to quell rising violence in Afghanistan, and has grown frustrated with the reluctance of some European members to either increase their contribution or deploy to more dangerous regions.

"Of course we are ready to consider what is necessary, but it must be part of a burden-sharing exercise where different countries play their part," British Prime Minister Gordon Brown told reporters.

NATO''s force in Afghanistan includes about 20,000 troops from the United States and 8,000 from Britain — the two highest contributors. U.S. President-elect Barack Obama has said he plans to add about 7,000 or 8,000 troops to the NATO mission.

In addition, there are some 12,000 U.S. troops in the country operating outside NATO''s command.

Germany in September approved an increase of 1,000 troops for Afghanistan, for a maximum of 4,500 German troops in the country. However, politicians have kept German soldiers from deploying to Afghanistan''s volatile southern reaches, where mainly U.S. forces are locked in a tough fight against al-Qaida and Taliban militants.

Canada, Italy and France each contribute around 2,500 troops to the NATO mission, and the Netherlands 1,700. Australia and Poland each sent around 1,000, and dozens of other nations provide smaller numbers.