Yemeni loyalists retook coastal areas near the strategic Bab al-Mandab Strait from Shiite rebels Thursday and were besieging a city further north, officials said.
The troops, backed by a Saudi-led coalition, seized Bab al-Mandab and Dhubab in the southern province of Taez near the strait at the entrance to the Red Sea, loyalist military official Abedrabbo al-Mihwali told AFP.
"We managed today to take back Bab al-Mandab and Dhubab with heavy fighting after having received reinforcements from Aden," Yemen's second city 150 kilometres (90 miles) to the south, he said.
Up to 23 rebels and 15 loyalists died in the fighting, Mihwali said.
President Abedrabbo Mansour Hadi and his government returned to Aden last month following six months in exile, after loyalists regained control of the city and four other southern provinces from the rebels.
The rebels still control the capital and northern provinces near the border with Saudi Arabia.
Loyalists and coalition forces then pursued the rebels and their allies, soldiers who remain loyal to former president Ali Abdullah Saleh, north to the Red Sea port city of Mokha, he said.
Fighting broke out Thursday afternoon as loyalists and coalition forces surrounded the city, he added.
Loyalist military sources, including an officer, confirmed that the areas of Bab Al-Mandab and Dhubab had been retaken.
"The Yemeni army and coalition forces are now seeking to retake Mokha and the rest of the Taez province to better secure Aden," another military source said.
Last month, loyalist forces began a major ground offensive in the central Marib province east of the capital.
Meanwhile, the Emirati army announced Thursday that one of its soldiers died in a German hospital after he was wounded in Yemen.
He had been fighting in Marib, news agency WAM quoted the army as saying.
So far, the United Arab Emirates have lost 62 soldiers fighting as part of the coalition, including 53 who died after a single missile attack in Marib early last month.