UAE-backed southern separatists overrun barracks in Yemen's Aden

Southern separatists gained ground across Yemen's second city Aden on Saturday and surrounded the presidential palace as they fought fierce battles with loyalist forces, military and security sources said.

Deadly fighting raging in Aden since Wednesday is pitting unionist forces loyal to the internationally recognised government against a force that supports it but is dominated by fighters seeking renewed independence for the south.

The force, known as the Security Belt, overran three military barracks belonging to unionist forces and were surrounding the presidential palace, sources close to the Security Belt said.

Fierce clashes were also taking place in several other parts of the city.

Southern Yemen was an independent state until 1990 and the north is widely perceived to have imposed unification by force.

The Security Belt is a force trained by the United Arab Emirates, a key partner in a Saudi-led military coalition which intervened in Yemen more than four years ago to prop up Hadi's government in the face of an uprising by Iran-aligned Shia Houthi rebels.

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The Houthis control large parts of northern and western Yemen, including the capital Sanaa.

On Thursday, Hadi's government urged Saudi Arabia and the UAE to put pressure on the Security Belt to avoid a military escalation in Aden.

Fighting in the city flared on Wednesday after two members of the Security Belt were killed in clashes with other loyalist forces after the funeral of police personnel killed in the city last week, according to security officials.

A missile and drone attack by Houthi rebels on a Security Belt training camp just outside Aden last week killed 49 people, many of them newly graduated cadets.

The UN human rights office this week accused the Security Belt force of "reportedly carrying out and enabling retaliatory attacks against civilians" from northern Yemen.

On Wednesday, the UN envoy to Yemen Martin Griffiths wrote on Twitter that he was "alarmed by the military escalations in Aden".

Clashes between the two sides have left at least 18 dead since Wednesday and scores of wounded, medics and security sources have said.

On Friday, Doctors Without Borders (MSF) tweeted that it had treated 75 people in one of its hospitals in Aden since Thursday night.