Yemen says it has foiled an al-Qaeda plot to blow up oil pipelines and seize some of the country's main ports, the BBC reported Wednesday.
Security remains tight, with hundreds of armored vehicles deployed to protect key targets.
The BBC also cites reports that the US preparing special operations forces for possible strikes against al-Qaeda in Yemen.
The news site says it appears that Yemen was at the center of “a complex and audacious plot which – had it succeeded – would have given al-Qaeda control over a crucial aspect of the country's infrastructure.”
A Yemeni government spokesman was quoted as saying the plot involved blowing up oil pipelines and taking control of certain cities – including two ports in the south, one of which accounts for the bulk of Yemen's oil exports and is where a number of foreign workers are employed.
"There were attempts to control key cities in Yemen like Mukala and Bawzeer," the spokesman said.
"This would be co-ordinated with attacks by al-Qaeda members on the gas facilities in Shebwa city and the blowing up of the gas pipe in Belhaf city.".
Al-Qaeda members dressed as soldiers were intended to invade the port facilities and take them over.
The US State Department on Tuesday ordered all non-essential staff out of Yemen and told US citizens to leave the country "immediately" over terrorism concerns, reported the AFP news agency.
The latest warning comes after the closure of some two dozen US missions across the Middle East and Africa and reports of intercepted messages from Al-Qaeda's top leader ordering its Yemen franchise to carry out an attack.
A US drone strike has killed at least four suspected al-Qaeda fighters in Yemen's eastern Marib province, a tribal source told AFP.
The raid targeted their vehicle "and turned it into a ball of fire, immediately killing the four, all of whom are Yemeni", the source said on Tuesday.
The electronic intercept that prompted the U.S. government to close embassies in 22 countries apparently was a conference call between al Qaeda’s senior leaders and representatives of several of the group’s affiliates throughout the region.
“This was like a meeting of the Legion of Doom,” one U.S. intelligence officer told The Daily Beast, referring to the coalition of villains featured in the Saturday morning cartoon Super Friends.