Shiite militia fought pitched battles with the army in Yemen's capital and the prime minister's convoy came under fire Monday in the biggest challenge yet to President Abdrabuh Mansur Hadi's rule.

Officials reported that the militia, known as Huthis, had seized control of state media, as they tightened their hold on Sanaa after overrunning the capital in September.

Gunmen on Saturday seized Yemeni President Abdrabuh Mansur Hadi's chief of staff, whose nomination as prime minister last year was rejected by Shiite militiamen controlling the capital, an official said.

The Huthi militia, who overran Sanaa last September, are suspected of being behind the abduction of Ahmed Awad bin Mubarak, the official added.

A car bomb tore through dozens of Yemenis lined up at a police academy in Sanaa on Wednesday, killing more than 30 in the latest attack highlighting the country's growing instability.

Police said at least 33 people had died and 62 were wounded in what it described as a "terrorist bombing" targeting potential police recruits, in a statement cited by the official Saba news agency.

A bomb wounded six Shiite militiamen in the Yemeni capital on Monday, a security official said, the latest in spate of attacks on the Huthi fighters who overran Sanaa in September.

The blast hit a post of the Huthis' police force in the Hayel district of Sanaa, the official said.

The death toll from a suicide bomb attack on a religious celebration by Shiite militia supporters in central Yemen has risen to 49, hospital sources said Thursday.

Medics told Agence France Presse that 49 people were killed and 70 wounded in Wednesday's attack carried out by a bomber dressed as a woman in the mainly Sunni city of Ibb, held by the Huthi Shiite militia.  

Shiite rebels, who have been advancing into mainly Sunni areas of Yemen, met deadly resistance on Friday from Sunni tribesmen as well as Al-Qaida militants, tribal and security sources said.

Heavily armed tribesmen battled the rebels around the city of Ibb, southwest of the capital, which the rebels entered earlier this week, the sources said.

Shiite rebels seized a strategic port city Tuesday to widen their fast-expanding zone of control, hours after a new premier was named in a bid to defuse Yemen's escalating political crisis.

And with the weakening of central authority, battered by the rebels' seizure of Sanaa last month, southern separatists were stepping up their demands for independence.

At least 47 people were killed when a powerful suicide bombing ripped through the Yemeni capital on Thursday, plunging the violence-plagued state into further turmoil after weeks of political deadlock.

Dozens more were wounded in the attack in Sanaa's Al-Tahrir square, which targeted a gathering for supporters of Shiite insurgents who overran the capital last month.

Shiite rebels who breezed into the Yemeni capital unopposed last month are now widely thought to be moving to cement their grip by snatching a strategic strait and oilfields.

The militiamen known as Huthis stormed into Sanaa on September 21, easily seizing key government installations, and they now man checkpoints and run patrols across the city in almost total absence of the security forces.

Hundreds took to the streets of Yemen's capital on Tuesday for the second protest this week demanding that Huthi rebels who seized control of Sanaa leave.

The rebels overran the capital 10 days ago in a lightning offensive and have maintained a strong military presence, conducting patrols and manning checkpoints.