Somalia's U.N.-backed federal government is hailing the news that al-Qaida-linked al-Shabab militants have begun pulling out of Mogadishu.

In a statement Saturday, Prime Minister Abdiweli Mohamed Ali said it is a “tremendous step forward” towards a more stable Somalia. He said the al-Shabab retreat was the result of military operations earlier in the week by the Somali army and African Union peacekeepers.

A spokesman for the AU peacekeepers also hailed what he called a “defeat” for al-Shabab. The spokesman said this was “the beginning of the end for al-Shabab.

But an al-Shabab spokesman said the retreat was a strategic move and said al-Shabab will remain in other towns in southern Somalia.

And the top United Nations official for Somalia welcomed the news, but cautioned that “real security risks,” including possible terrorist attacks, remain and “must not be underestimated.”

Al-Shabab said it began leaving its positions in Mogadishu late Friday.

Al-Shabab has been fighting to topple the government. The Islamist group also has made it much more difficult for food aid to be dispersed to millions of victims of drought and famine across Somalia.

Both the AU spokesman and Prime Minister Abdiweli said it would now be easier for international aid groups to supply food and other aid to the city.

The United Nations says thousands of Somalis have already died from the effects of the drought. The crisis has forced hundreds of thousands of Somalis to flee their homes in search of food and water. Many have gone to camps in Mogadishu, while others have fled to crowded refugee camps in Kenya or Ethiopia.