The Houthis have regained several positions lost in recent months across southern Yemen, in a fresh push towards the Gulf-backed government's temporary headquarters in the port city of Aden, military sources said on Sunday.

In Lahj province, which borders Aden, sources told AFP that Houthi fighters are now positioned on a hill overlooking the strategic Al-Anad airbase.

The base at present houses Sudanese forces from a Saudi-led coalition that has been battling the Houthis across Yemen since March.

The Houthi deployment near Al-Anad, which took place without fighting, "poses a real danger to pro-government and coalition forces," a military source told AFP.

Backed by coalition strikes, supplies and troops, loyalist forces launched a major counter-offensive in July, pushing the Houthis, who are based in the north of Yemen, out of Aden and four other southern provinces - Lahj, Daleh, Abyan, and Shabwa.

Meanwhile, in Al-Madaribah in southwestern Yemen on the border between Lahj and Taez provinces, fighting on Saturday between the Houthis and troops loyal to the government left casualties on both sides, according to pro-government sources.

The Houthis also retook the second city in Daleh province, Damt, after besieging it for hours and clashing with loyalist troops there, military sources said.

These clashes left 16 people dead, the sources said, adding that many others were wounded.

Forces fighting in support of President Abd Rabbuh Mansour Hadi "were forced to withdraw from the city," one of the sources said.

In the coastal city of Dhubab, near the Bab al-Mandab strait, the Houthis seized a military base following clashes with pro-government troops that left six loyalists and 11 Houthis dead, another military source said.

Pro-government troops seized Dhubab early last month, giving them effective control of Bab al-Mandab, through which much of the world's maritime traffic passes.

The Iran-supporte Houthis, a Shiite minority from Yemen's north, seized control of capital Sanaa last year and then advanced south, forcing Hadi to flee to Saudi Arabia as they moved on to Aden.

They have allied with forces loyal to ousted strongman Ali Abdullah Saleh.

Ministers returned to Aden in mid-September after six months in Saudi exile after fleeing with Hadi, who designated the city, which has seen an increasingly desperate humanitarian situation as fighting has continued, as a temporary capital.

Emirati soldiers return

The Houthi advance comes as the United Arab Emirates, which has lost 68 soldiers during coalition operations, welcomed the first of its troops returning from Yemen.

While Emirati media reported that its soldiers had been replaced by a second deployment, Western sources this week indicated that only a limited number of UAE special forces will now remain in Yemen.

An official of the Fourth Military Region in Aden told AFP that "the Houthis and their allies are seeking through their latest advances to return to Aden".

He spoke of a shortage in arms and ammunition among pro-government fighters in the south.

The UN says that around 5,000 people have been killed in Yemen's conflict since it escalated in March.