* Security Council to debate issue soon
* U.N. mission struggling to contain insurgency
WASHINGTON, Oct 20 (Reuters) - The United States supports proposals to raise more African Union troops for Somalia and the U.N. Security Council will likely debate the matter within 30 days, a senior U.S. diplomat said on Wednesday.
Assistant Secretary of State Johnnie Carson said Uganda and other countries had been pressing to increase 7,200-strong AMISOM mission, which is struggling to stabilize Somalia in the face of an insurgency by the al Qaeda-allied al Shabaab militia.
"In principle we support the increase in the number of troops on the ground, but do not take a position on what that number should be," Carson, Washington's top diplomat for Africa, told an audience at a Washington think tank.
"This issue is likely to be discussed and debated in the U.N. Security Council in the next 30 days," he said.
Ugandan President Yoweri Museveni said this month that the U.N. Security Council was considering more funding for an expanded AU peacekeeping mission, and that Uganda was ready to provide all of the 20,000 soldiers thought necessary to squelch the raging insurgency in the Horn of Africa country.
Uganda provides the bulk of the forces already on the ground, with a lesser number coming from Burundi, and Museveni has been urging greater effort to stabilize the country after al Shabaab claimed responsibility for twin bomb blasts in Uganda in July that killed nearly 80 people.
The presence of foreign AMISOM troops gives Somali militants a reason to pose as nationalist champions and wins them easy recruits and financial support at home and from Somalis abroad, analysts say.
Carson said the United States would continue to improve ties with Somaliland and Puntland -- two semi-autonomous regions in Somalia that are seen as relatively stable -- while working to buttress the Western-backed Transitional Federal Government, which controls only a part of the capital Mogadishu.
He said the international community, including Arab states, should do more to turn the tide in Somalia, which he described as an increasingly global threat to security and trade as pirates prowl the seas off the Horn of Africa.
Carson said the United States, which has donated $229 million to support the AU peacekeeping effort as well as more than $200 million in unilateral humanitarian and development assistance, would have to remain involved if the threat posed by Somalia's collapse is to be contained.
"It's always nice to have a clear road map to an exit," Carson said, while quickly saying that no such easy answers exist for the situation in Somalia.
"This is going to be a long, sometimes uncertain, difficult process," he said. (Reporting by Andrew Quinn; Editing by Philip Barbara)