Sixteen Yemeni pro-government fighters were killed on Tuesday in separate clashes with Houthi rebels and Al-Qaeda fighters in the south of the war-torn country, military sources and officials said.

Forces supporting Yemen's President Abedrabbo Mansour Hadi, backed by a Saudi-led coalition, are fighting both the Huthi rebels who control parts of the country including the capital Sanaa and Islamist militants in the south.

Al-Qaeda fighters on Tuesday ambushed an army unit on its way to conduct an operation against a Islamist militant position east of the coastal town of Shaqra in the southern province of Abyan, security sources said.

Local officials said 11 soldiers and 15 Al-Qaeda fighters were killed in the attack.

Al-Qaeda fighters seized two military vehicles and weapons, security sources said.

Meanwhile, in the neighbouring province of Shabwa, five pro-Hadi fighters including an officer were killed along with nine Houthi rebels near the town of Baihan, loyalist military sources said.

Baihan is held by the Shia Houthis and their allies, supporters of former president Ali Abdullah Saleh.

Al-Qaeda and the rival Islamic State (IS) militants have taken advantage of chaos in Yemen to reinforce their presence in the Arabian Peninsula country.

Yemen's war has killed more than 7,000 people since the Saudi-led coalition began its military intervention in March 2015, according to the United Nations.