Yemen's national unity government, headed by the opposition, was sworn in Saturday to lead a three-month transition period until early polls are held and President Ali Abdullah Saleh formally steps down.

The official Saba news agency said the swearing-in ceremony took place at the Republican Palace in the capital Sanaa in the presence of Vice President Abdrabuh Mansur Hadi.

The new 34-member cabinet, headed by Prime Minister Mohammed Basindawa, will carry out its duties until February elections, after which Hadi will take over the presidency for an interim two-year period as stipulated by a Gulf-sponsored deal drafted to resolve Yemen's political crisis.

"Yemen expects this government to improve conditions for a peaceful life for citizens," Hadi said, chairing a first cabinet meeting. "Our primary duty is for the country to emerge from its economic and security collapse."

In Oslo, meanwhile, after receiving the Nobel Peace Prize on Saturday, Arab Spring activist Tawakkol Karman said the international community had failed to provide enough support for the deadly anti-Saleh uprising in Yemen.

The activist said the struggle for democracy in her country "did not get the international understanding, support or attention of the other revolutions in the region."

"This should haunt the world's conscience," said the 32-year-old mother of three in her acceptance speech after becoming the first Arab woman to receive a Nobel in any category.

Interviewed after the award ceremony, Karman lamented that she was barred from running in Yemen's February presidential election.

"I want to (be a) candidate," she told CNN.

"If I will (be a) candidate, I will win," she added, noting that she can't contest because the vice president has been declared the only eligible candidate.

Half of the new cabinet posts were entrusted to members of the opposition Common Forum, while Saleh loyalists were appointed to the other half, a condition stipulated in the Gulf plan signed by Saleh on November 23.

Saleh's ministers for foreign affairs and defence have retained their posts, while the interior ministry, the human rights portfolio, finance and information ministries have been entrusted to the opposition.

The Gulf initiative gave Hadi temporary authority to rule Yemen and form a unity government until elections in which he will be the only candidate.

Once Hadi is elected, Saleh will then lose his current title of honorary president and officially be removed from power.

The power-transition deal also gave Saleh and his close relatives immunity from prosecution for crimes he allegedly committed in the uprising against his rule that has left hundreds of people dead and thousands more wounded since it began in January.

However, the protesters who have thronged the streets of the capital and other Yemeni cities have rejected the immunity clause and continue to demand that the long-time dictator go on trial.

On Saturday, thousands of protesters marched in Yemen's flashpoint city of Taez, demanding Saleh be tried. "No immunity, no assurances," chanted the protesters.

Taez has witnessed some of the worst violence in the months of unrest, as armed tribesmen who have thrown their support behind the protesters continue to battle Saleh's troops.

In the past week alone, more than 30 people have been killed in the fighting.

Resolving Yemen's deteriorating security situation will likely be the most difficult challenge facing the new government.

Saleh's sons and nephews still control much of the country's elite military units, and unresolved conflicts with rebels, separatists and Al-Qaeda militants continue to threaten stability.

In the latest violence, weekend clashes in southern Yemen left two government soldiers and 11 suspected members of Al-Qaeda dead, military and local sources said on Saturday.

The capital Sanaa remains divided, with pro-Saleh troops controlling some neighbourhoods, and dissident soldiers under the control of Saleh's arch rival, defected General Ali Mohsen al-Ahmar, controlling other areas.