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 AFP.
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.
The BBC reported Tuesday that hundreds of armored military vehicles have been deployed in the Yemeni capital of Sanaa to secure the presidential palace, vital infrastructural buildings and Westerns embassies in the capital.
A security source confirmed to the BBC that Yemeni intelligence services had discovered that tens of al-Qaeda members had arrived in Sanaa over the past few days in preparation for the implementation of a large and dangerous plot. The source suggested that the plot includes “explosions and suicide attacks aimed at Western ambassadors and foreign embassies in Yemen, in addition to operations aimed at the Yemeni military headquarters.”
The US drone strike has killed at least four suspected al-Qaeda fighters in Yemen's eastern Marib province, a tribal source has told the AFP news agency.
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.
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.
Among those killed in the drone strike was an al-Qaeda operative listed by Yemeni authorities on Monday, the source said.
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.
According to Al Jazeera, Waeli is on a government list of 25 al-Qaeda suspects wanted in connection with an alleged plot to launch a major attack before Ramadan ends and the Muslim Eid al-Fitr feast begins, either Thursday or Friday.
The New York Times reported that electronic intercepts last week revealed that Al Qaeda boss Ayman Al-Zawahiri had ordered Nasser al-Wuhayshi, the head of al-Qaeda in the Arabian Peninsula (AQAP), to carry out an attack.