A US drone strike killed four Al-Qaeda suspects in Yemen Tuesday, a tribal source said, amid heightened security across the Middle East against a possible major attack by the jihadists.

Those killed included one of 25 Al-Qaeda operatives listed late on Monday by the Yemeni authorities as among those plotting attacks to coincide with the ending of the Muslim holy fasting month of Ramadan later this week, the source told AFP.

The raid in Yemen's eastern Marib province targeted their vehicle "and turned it into a ball of fire, immediately killing the four militants," the source said, adding that all those killed were Yemenis.

Yemen's official Saba news agency confirmed "the death of four Al-Qaeda militants in Wadi Abida in Marib."

The tribal source named two of the dead as Saleh al-Tays al-Waeli and Saleh Ali Guti.

Waeli figures on the list of 25 Al-Qaeda suspects wanted in connection with an alleged plot to launch a major attack before Ramadan ends and the Eid al-Fitr feast begins, either Thursday of Friday.

Yemen promised a five million rial reward (about $23,000) in return for information that could lead to the arrest of any member of the group, the defence ministry's news website 26sep.net reported.

Among those listed is the Saudi Ibrahim al-Rubaish, a former Guantanamo prisoner who fled to Yemen after being repatriated to Saudi Arabia.

He is believed to be the mastermind behind providing Al-Qaeda in the Arabian Peninsula with theological justification for its operations.

Saudi Arabian explosives expert Ibrahim al-Assiri is also on the list.

About two dozen US diplomatic posts have been shuttered across the Middle East since Sunday after Washington said electronic intercepts of high-ranking Al-Qaeda operatives signalled a major attack was imminent.

US media said Tuesday that intercepts between Al-Qaeda chief Ayman Al-Zawahiri and the leader of the group's Yemen affiliate had sparked the closures as well as a global travel alert.

The New York Times said that the electronic communications last week revealed that Zawahiri had ordered Nasser al-Wuhayshi, the head of Al-Qaeda in the Arabian Peninsula, to carry out an attack as early as this past Sunday

Tuesday's drone strike is the fourth of its kind since July 28. The raids have killed 17 suspects in one week.

Al-Qaeda in the Arabian Peninsula is seen as the terror network's most capable franchise following the decimation of its core leadership in Afghanistan and Pakistan in recent years.

The Yemen-based group has attempted a number of attacks on US soil, including a bid to bring down a passenger plane in 2009 by a man wearing explosives in his underwear and a failed plot to send bombs concealed in printers.

The United States in turn has launched scores of drone strikes in Yemen, where the militant groups thrive in vast, lawless areas largely outside government control.

Several US allies, including Britain, France, Germany and Norway have also announced closures of some of their missions in the region.

The US closure list includes 15 embassies or consulates that were shut on Sunday -- the fifteenth anniversary of Al-Qaeda's attacks on US embassies in East Africa -- as well as four additional posts.