Aden (AFP) - A suicide car bombing killed four people Monday when it hit a gathering of loyalist forces in Yemen's Aden, the southern city serving as a government base, a security official said.

Five others were wounded in the attack in the Sheikh Othman district of the port city, the official said.

The suicide bomber rammed his explosives-laden vehicle into an area where security forces and pro-government militiamen had assembled, the official said.

President Abedrabbo Mansour Hadi has declared Aden as Yemen's temporary capital as Sanaa remains in the hands of the Iran-backed Huthi rebels and their allies since they seized it in September 2014.

Al-Qaeda and the Islamic State group have stepped up attacks in Aden despite the efforts of the government and its backers in a Saudi-led coalition battling the Huthis and their allies to secure it.

On February 17, a suicide bombing claimed by IS killed 14 soldiers. The attacker detonated his explosive vest among soldiers at a training session.

The rebels controlled Aden for months before government loyalists pushed them out in July.

Because of the unrest gripping Aden, Hadi himself and many senior government officials spend most of their time in Riyadh, which has led an anti-rebel coalition since March 26 last year.

Meanwhile, two people were killed and two others wounded in an explosion in their family home in northwestern Aden, a local official said.

An explosive device went off as the family returned to their house for the first time since they fled in August during fighting between rebels and loyalists, the official added.

Further north, 12 soldiers were killed Sunday when a rocket slammed into a base of pro-Hadi forces in Marib, east of Sanaa, military sources said.