The United States said on Monday that it has closed its embassy in Yemen to the public until further notice due to security concerns.
"Due to the recent resignation of the Yemeni president, prime minister, and cabinet, and the ongoing security concerns, the US embassy in Sanaa is unable to provide routine consular services and will have very limited ability to assist with emergency cases involving US citizens," the embassy said on its website.
"The US embassy will be closed to the public until further notice out of an abundance of caution and care for our employees and others who may be visiting the embassy," it said.
The statement was issued only hours after a drone strike reportedly killed three Al-Qaeda suspects in an eastern desert area of Yemen. The United States is the only country operating the unmanned aircraft in the region.
US President Barack Obama insisted Sunday his administration would pursue its efforts against Al-Qaeda in Yemen regardless of upheaval that has seen Western-backed President Abdrabuh Mansur Hadi tender his resignation along with Prime Minister Khalid Bahah.
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Yemen's parliament has so far postponed a session to consider Hadi's resignation, raising fears of a prolonged power vacuum after a Shiite militia kidnapped his chief of staff and seized key buildings across the capital Sanaa.
"The US Department of State warns US citizens of the high security threat level in Yemen due to terrorist activities and civil unrest" and urges them "not to travel to Yemen," said the embassy statement.
"US citizens still in Yemen should make plans to depart immediately," it said.
"We are continuously analysing the security conditions and will resume consular operations as soon as our analysis indicates we are able to do so safely."
The unrest has raised fears of strategically important Yemen, which lies next to oil-rich Saudi Arabia and along key shipping routes, collapsing into a failed state.
Yemeni authorities have for years allowed the United States to carry out strikes against Al-Qaeda in the Arabian Peninsula (AQAP), and Hadi has been a key US ally in fighting the jihadist group.