Yemeni military officials say pro-government troops have been besieging a military base held by Shiite rebels for 40 hours, after cutting off major supply routes to the facility.

The officials, speaking on condition of anonymity because they're not authorized to talk to reporters, said Tuesday the troops are besieging the al-Anad base as part of their push north of the city of Aden, which they captured earlier this month.

A humanitarian pause in the fighting has failed to take hold. The officials also say that troops trained by the Saudi-led coalition, which is conducting an air campaign against the rebels known as Houthis, are heading to reinforce pro-government fighters.

Al-Anad, once the site of U.S. intelligence operations against al-Qaida in Yemen, is the main rebel encampment in the country's south.