At least three soldiers were killed and five others injured in an attack launched by unknown gunmen against crude oil tankers in the country's southeastern province of Shabwa on Tuesday, a military official said.

"Soldiers securing crude oil tankers were targeted by a group of gunmen when travelling through a main road linking the provinces of Shabwa and Hadramout," the local military source said on condition of anonymity.

All the casualties were from 37th Armored Brigade and "the pro-government forces will carry out a manhunt operation to track the perpetrators," the source added.

The official held militants of the Yemen-based al-Qaida in the Arabian Peninsula (AQAP) responsible for the attack.

The AQAP network has exploited years of deadly conflict between the Yemeni government and Houthi rebels to expand its presence in the war-ravaged Arab country.

Attacks carried out by militant groups against the pro-government southern troops securing oil fields have recently surged in various regions of Yemen as a UN-brokered nationwide truce expired without reaching a renewal agreement between the warring sides.