Mogadishu - Somali President Abdullahi Yusuf Ahmed on Tuesday appointed a new prime minister, defying a vote by parliament not to approve his decision to sack Prime Minister Nur Hassan Hussein.

"After I consulted lawmakers, I today appointed Mohamed Mohamoud Guled Ga'madhere as prime minister," Yusuf told reporters in Baidoa, the seat of the Somali parliament. "I appointed the premier after I carefully considered the wrong decision parliament took yesterday."

Yusuf on Sunday fired Hussein and his cabinet, saying he was "unable to perform his duties" and that he was obliged to act to save the country.

However, parliament on Monday voted overwhelmingly to back Hussein, who said the decision to fire him was unconstitutional.

Yusuf has been at loggerheads with his prime minister since the summer, when Hussein fired the Mogadishu mayor, a close ally of Yusuf.

The decision to defy parliament and appoint Guled is likely to only increase the political infighting, which Islamist insurgents have taken advantage of to advance to the edge of Mogadishu.

Somalia has been embroiled in chaos ever since the 1991 ouster of dictator Mohamed Siad Barre.

The crisis has deepened since Ethiopian forces helped kick out a hardline Islamist regime in the last half of 2006, sparking a bloody insurgency that has killed over 10,000 civilians.

The African Union on Sunday blasted the infighting and called on the two leaders to put their differences behind them and focus on bringing peace to the Horn of Africa nation.

Hussein, who came to power last November, has accused Yusuf of trying to derail the UN-sponsored peace process between the Transitional Federal Government and opposition group the Alliance of the Re-Liberation of Somalia (ARS).

Guled said he would continue to make efforts to bring peace.

"I will keep working at the reconciliation process and will consult all Somali sides," he said after his appointment.

The step up in the political problems comes as Ethiopia prepares to pull its troops out of Somalia, perhaps to be closely followed by the African Union peacekeeping force.

Main insurgent group al-Shabaab has refused to take part in the peace process and there are fears that it will overrun Somalia completely should the Ethiopians and AU leave.

Yusuf has admitted that the government now only controls parts of Mogadishu and the town of Baidoa. (dpa)