Suspected al-Qaeda militants killed four Yemeni soldiers in their sleep early yesterday in an attack on forces guarding the country’s only liquefied natural gas (LNG) export terminal, a local official said.

The assault follows an escalating campaign of drone strikes by the US over the past two weeks and warnings of militant attacks that prompted Washington to close embassies across the Middle East and evacuate some staff from Yemen.

The official said the gunmen infiltrated a checkpoint guarding the Balhaf LNG terminal in the southern Shabwa province, killed one soldier and then entered a cargo container where four more troops were sleeping and shot them dead.

The attackers fled in a vehicle, he said.

The gunmen infiltrated a checkpoint

A Yemeni government spokesman said last week that the $4.5 billion gas facility, jointly managed by Yemen LNG and France’s Total, was one of two energy targets that suspected al-Qaeda militants had been plotting to attack.

Washington stepped up drone strikes on suspected al-Qaeda targets in Yemen which killed at least 15 people in three days.

US ally Yemen, one of the poorest Arab countries, is the base for al-Qaeda in the Arabian Peninsula (AQAP), one of the most active branches of the network founded by Osama bin Laden, and militants have launched attacks from there against the West.

The Balhaf facility, the largest industrial project ever undertaken in Yemen, opened in 2009. It is heavily guarded by Yemeni troops.

It supplies gas cooled to liquid for export by ship, under long-term contracts to GDF Suez, Total and Korea Gas Corp.