The United States and United Kingdom have told their citizens in Yemen to leave the country immediately due to the threat of "terrorist attacks", the US state department and UK's foreign office have said Al Jazeera reported.
The State Department also said it had ordered all non-essential US government staff in Yemen to leave the country.
The new US measures, announced in a statement on Tuesday, followed a heightened security warning from Washington on Friday that prompted the closure of several Western embassies in Yemen and several US missions across the Middle East and Africa.
It also came after at least four suspected al-Qaeda members were killed in what local tribal leaders said was a US drone strike in central Yemen early on Tuesday.
"The Department urges US citizens to defer travel to Yemen and those US citizens currently living in Yemen to depart immediately," the statement posted on its website said.
"On August 6, 2013, the Department of State ordered the departure of non-emergency US government personnel from Yemen due to the continued potential for terrorist attacks," it added.
The UK's foreign office, meanwhile, advised against all travel to Yemen, and "strongly urge[d] British nationals to leave now". It said that all British embassy staff had been temporarily withdrawn from the country.
Tuesday's warning came after US media reports indicated that the increased threat levels were the result of what US intelligence officials said were intercepted communications between top al-Qaeda leaders.
The New York Times reported on Monday that the closure of the embassies was the result of intercepted electronic communications between Ayman al-Zawahri, who replaced Osama bin Laden as head of al-Qaeda, and Nasser al-Wuhayshi, the head of Yemen-based affiliate al-Qaeda in the Arabian Peninsula (AQAP).
US sources said that while some type of message between Zawahri and AQAP was intercepted recently, there were also other streams of intelligence that contributed to the security alert, which was prompted by a threat from AQAP.
"The threat picture is based on a broad range of reporting, there is no smoking gun in this threat picture," a US official told the Reuters news agency on condition of anonymity.
US officials said there was still no information about a specific target or location of a potential attack, but the threat to Western interests had not diminished.
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