The African Union is asking the United Nations Security Council to approve expanding its mission in Somalia, saying the gains made against Islamic insurgents must be protected.

AU Commissioner for Peace and Security, Ramtane Lamamra, told the Council in New York Wednesday that for the first time in 20 years, Somalia's transitional government controls nearly all of Mogadishu, the capital.

The Security Council provides funding for the AU mission and Lamamra is asking the diplomats to authorize another 5,000 troops for a total of 17,000. He is also appealing to the Council to provide helicopters and other support.

U.N. diplomats say it will take several weeks to work out the details of the AU request.

AU forces have made recent progress against al-Shabab — Islamic radicals who are trying to turn Somalia into a hardcore Muslim state. Somalia has been without a stable government since a 1991 coup.