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.
Late Sunday, 16 pro-Hadi soldiers were killed and six wounded when a landmine exploded as their vehicle passed in the city of Marib, east of the capital Sanaa, a military source said.
The blast took place on the road to the Sahn military base northwest of Marib, the source added.
Loyalists are in control of Marib while Sanaa is in the hands of the Iran-backed Huthi rebels who are also allied with forces loyal to ousted president Ali Abdullah Saleh.
The United Nations says that around 5,000 people have been killed in Yemen's conflict since it escalated in March.
UN chief Ban Ki-moon was leaving for Saudi Arabia Sunday amid a new push by the world body for peace talks in Yemen.
The United Nations is hoping to announce next week a date for talks between the government and the rebels.