"Seventeen soldiers were killed in the fighting," which erupted when the Islamist fighters attacked army positions in Mallah, a town in Lahij, an army officer on the ground told AFP.

Eleven others were missing and "believed dead," said the same source.

An official in the Al-Qaeda stronghold of Jaar, southeast of Lahij, said 12 militants were also killed.

"The air force and ground troops are now shelling an army post which Al-Qaeda militants have managed to take over" in Mallah, the army officer said.

Another military official said "two army tanks and three Al-Qaeda vehicles were destroyed in the fighting, (while) Al-Qaeda militants have seized several soldiers."

The attackers targeted the 119th and 201st army brigades, involved in military operations aimed at regaining control over Zinjibar, the capital of Abyan province southeast of Lahij, which the militants overran last May.

In a text message received by AFP, the Al-Qaeda-linked militants, who have named themselves Partisans of Sharia (Islamic law), claimed the attack which they declared as "Battle of Dignity."
They said "30 soldiers" were killed in the fighting but did not say how many of their men had died.

On Friday, Al-Qaeda members sabotaged a 320-kilometre (200-mile) gas pipeline linking Marib province to Balhaf terminal on the Gulf of Aden, all in the country's restive south.

The pipeline attack came shortly after two US drone attacks in eastern Yemen targeted Al-Qaeda suspects killing seven people, six of them militants, according to a local official in Shabwa province.

The army has been locked for months in deadly battles with the Partisans of Sharia who have exploited a central government weakened by a year of anti-regime protests to strengthen their grip.

They have launched deadly attacks against security forces, especially across south and southeast Yemen.

At the start of March, 185 soldiers were killed in a massive assault by Al-Qaeda militants on an army camp near Zinjibar.

The United States says the Yemen-based Al-Qaeda in the Arabian Peninsula, or AQAP, is the most active branch of the global terror network.