Discuss as:

Al-Qaida group al-Shabab withdraws from its last stronghold in Somalia

Stringer / AFP - Getty Images

The al-Qaida-allied al-Shebab militant group said it had left the city of Kismayo, seen above Friday, after it was attacked by a Kenya-Somalia force.

MOGADISHU, Somalia -- Somalia's al-Shabab rebels withdrew from the southern Somali city of Kismayo overnight, the rebel group and residents said Saturday, a day after Kenyan and Somali government forces attacked the militants' last bastion.

“We moved out our fighters ... from Kismayo at midnight,'' al-Shabab spokesman, Sheikh Ali Mohamud Rage, told Reuters.

He threatened to strike back soon. “The enemies have not yet entered the town. Let them enter  Kismayo which will soon turn into a battlefield,” he said.

African Union troops from Kenya, Uganda and Burundi have combined over the last 18 months to kick al-Shabab out of the Somali capital Mogadishu and take a series of smaller towns that the insurgents fled to.

Al-Shabab, which formally merged with al-Qaida in February, had earned money by collecting taxes on goods arriving at the Indian Ocean port, so the loss of the stronghold is a double blow to the armed fundamentalist group that began attacks in 2007 and went on to control all but a few blocks of the capital.

D-Day for al-Qaida in Somalia? Troops storm beaches at last stronghold

The assault is likely to send al-Shabab fighters underground. Hardcore fighters may unleash suicide bombs and ambushes but less dedicated fighters could melt back into their communities, further reducing al-Shabab's strength.

At an international one-day summit Britain's Prime Minister David Cameron said the world would "pay a price" if it fails to help Somalia overcome terrorism, piracy and starvation. ITV's Lee Comley reports. 


Born in the USA, but now among Somalia's Islamist terrorists

The African Union force said that some al-Shabab fighters have already contacted military officials in recent days, saying they wanted to defect from al-Shabab.

Expert: War on terror at 'critical' point as al-Qaida looks to regroup in Africa

Speaking on the sidelines of the U.N. General Assembly in New York Friday, Kenya's Deputy Prime Minister Musalia Mudavadi called the entry of Kenyan forces into the Somali port "a significant victory."

"This is a major blow to them and we think it's positive for the region and for Somalia," he said. 

More world stories from NBC News:

Follow World News from NBCNews.com on Twitter and Facebook