Insurgents in army uniforms stormed a hotel in the Somali capital Mogadishu frequented by government officials on Tuesday, killing at least 31 people including legislators, the government said.

The hardline Al Shabaab Islamists who have been fighting for three years to oust the fragile Western-backed "transitional government", and control most of the city, claimed the attack.

The Information Ministry said the 31 dead included six members of parliament and five government security personnel. "The blood of the dead is leaking out of the hotel," said Information Minister Abdirahman Osman.   

The assault underscored the failure of the government and more than 6,300 mostly Ugandan African Union peacekeepers to bring order after nearly two decades of anarchy, making Somalia a continual source of instability for east Africa.

Last month Al Shabaab expanded its reach as far as Uganda, claiming a double suicide bombing of packed bars in the capital Kampala, to put pressure on it to pull its troops out.

Those attacks killed more than 70 people and jolted the African Union into increasing the peacekeeping contingent and considering giving it a mandate to fight the rebels.

On Tuesday, Al Shabaab spokesman Sheikh Ali Mohamud Rage told reporters in Mogadishu that its fighters had "carried out an operation at Hotel Muna" and succeeded in killing government and intelligence officials, MPs and civil servants.

The Muna Hotel stands in one of the small nominally government-controlled areas of the capital, between the presidential palace and the Indian Ocean.

Osman said one gunman had been captured. His ministry said two others had blown themselves up, and that sporadic gunfire and shelling were continuing in the area.

"Some of the MPs had guns in their rooms and defended themselves before security forces arrived," said an anonymous government security source.

On Monday, the African Union announced the arrival of hundreds of new peacekeeping troops, mostly Ugandans, for the Amisom mission to help the government in its battle against Al Shabaab.

The force has so far been able to do little more than guard the airport and port and shield President Sheikh Sharif Ahmed. Somalia's members of parliament, the apparent targets of Tuesday's attack, do not benefit from this protection.

"We have the same enemies ... and I don't know why the MPs don't have the same security," said pro-government lawmaker Abdiladif Muse Sanyare.   

He was speaking from Nairobi, where many of the MPs say they have to live to feel safe, even at the risk of alienating ordinary citizens. The security source said more than 300 armed Al Shabaab fighters were thought to live in the supposedly government-controlled neighbourhood.   

"They disguise themselves as civilians running different smaller businesses and working in different restaurants and shops," he said. The insurgents control large areas of central and south Somalia, and have attracted a large number of foreign fighters to their cause.

Analysts agree that, despite their worries about Somalia serving as a base for international Islamist militancy, there is no appetite among Western powers to send forces to Somalia.

"What we are going to see is greater international support for Amisom, more training of its soldiers and a lot in the way of indirect attempts to support the transitional government (TFG)," said Will Hartley, terrorism analyst at IHS Jane's. "The international community is very much wedded to the TFG."    

But Rob Harford, operations director at Salamanca Risk Management, said even African peacekeepers, whom al Shabaab portray as foreign invaders, risk becoming part of the problem.

"Whether more African Union troops will lead to greater stability is the million-dollar question. Somalia is a particularly unstable and complex insurgency. Unless the soldiers are properly trained, their arrival will almost certainly lead to greater instability."    

More than 21,000 Somalis have been killed in the insurgency, 1.5 million have been uprooted from their homes and nearly half a million are sheltering in other countries in the region. - Reuters