The speaker threw a chair at his deputy on Sunday

A day after throwing a chair at his deputy in a hotel in the Kenyan capital, Mr Isaak told a news conference that his government had impeached the incumbent president, Abdulkassim Salat Hassan.

Somalia has been without an effective central government since the overthrow of President Siad Barre in 1991.

A transitional national government (TNG) was set up 2000 but only controls part of the capital, Mogadishu.

This latest announcement will do little to boost the credibility of the TNG as a united force at the ongoing Somali peace talks in Nairobi.

Mr Isaak said that he would head the TNG until a new president is appointed, although his claim is unlikely to be taken seriously by most Somalis.

The BBC's Yusuf Hassan, who attended the news conference, says that many delegates regard Mr Isaak's action as unconstitutional.

The delegates maintain that it is only the Somali supreme court that has powers to declare a new president.

Fight

The declaration by Mr Isaak was made just one day after he was involved in a fight with his deputy, Mohamed Abdi Yusuf, at a Nairobi hotel.

Mr Isaak, who was chairing a meeting of the TNG delegates, threw a chair at Mr Yusuf following a disagreement.

However, Mr Yusuf was not injured.

In January this year, a Somali professor, Mohammed Abdi Gandhi, had his arm broken by thugs hired by warlords at an earlier round of the peace talks in the western Kenyan town of Eldoret.

Meanwhile, about 40 clandestine immigrants, including Africans and gypsies, occupied the disused Somali embassy in Paris to protest at the introduction of tougher French immigration laws.

The clandestine immigrants say the laws, which impose tougher entry and residence conditions, are anti-democratic.

The Somali embassy premises have been empty for the past 12 years because the country has had no diplomatic representation.