A suicide car bomber linked to al-Qaeda has rammed into a field hospital run by a Shia rebel group east of Yemen's capital, killing at least 15 people, while five more died in an ambush in the south of the country, according to local sources.

The suicide car bombing took place in the town of Majzar in Maarib province, tribal sources told Al Jazeera.

"The attack targeted Houthi rebels in the hospital that they occupied last month and they are using as their headquarters," said Al Jazeera's Mohamed Vall, reporting from Sanaa.

The armed group Ansar al-Sharia, a branch of al-Qaeda in the Arabian Peninsula (AQAP), claimed responsibility for the bombing in a statement on its Twitter account.

Local tribesmen said at least 15 people were killed in the attack and more than 50 were wounded.

In the second attack, local officials said fighters ambushed a car used by Houthi fighters, killing five of them. An al-Qaeda statement put the Houthi death toll in the attack at six.

There was no immediate word from the Houthi rebels, who are named after the tribe of their leader and founder.

The Houthis swept through the capital earlier this month after consolidating their grip over northern provinces.

Ansar al-Sharia had previously carried out numerous attacks on military and civilian installations of the US-allied Yemeni government. However, the group, which adheres to an austere brand of Sunni Islam which views Shia Muslims as heretics, has turned its attention to the Houthis after they captured Sanaa.

Last week, they said they carried out a similar attack on the Houthis in their northern stronghold of Saada province, in which dozens were killed or wounded.

Anti-Houthi rally

Meanwhile, hundreds of protesters from the February 11 Revolution movement marched along the main Zubairi road in Sanaa on Sunday, chanting slogans against the Houthis.

"We don't want Houthis any more," shouted the demonstrators, whose movement was behind the 2011 uprising which ousted former President Ali Abdullah Saleh.

They urged the rebels to "apologise to the Yemeni people" and implement a UN-brokered peace accord, including a security protocol that stipulated their withdrawal from Sanaa once a new prime minister is named.