Britons in Yemen must flee now on commercial flights or risk being stranded amid escalating violence as the UK will not be able to evacuate them, Foreign Secretary William Hague has warned.
In the starkest warning he has issued so far to UK nationals still in the Gulf state - believed to number a few hundred - he said they "should not plan for nor expect" the British Government to be able to get them to safety.
Clashes between the regime of President Ali Abdullah Sanah and opposition tribesmen intensified on Friday as rockets rained down on the presidential palace, killing seven guards and wounding the president and eight senior officials.
The White House said the violence was "senseless" and called on all sides to cease hostilities and pursue a peaceful process of transferring power.
Mr Hague - who made a similar appeal a week ago - said people must not hesitate about quitting Yemen and urged people with friends and relatives in the country to tell them to leave immediately.
"This extremely serious escalation of violence in Yemen underscores our clear message that British nationals in Yemen should leave immediately while commercial flights are still operating," he said.
"Given that we cannot expect forewarning of any airport closures, British nationals should not wait to leave.
"The British Government has been advising British nationals to leave Yemen since March 12 and we will not be in a position to evacuate those who do not leave on commercial airlines while these are still flying.
"I ask those in the UK with friends and relatives in Yemen to pass this message on and tell them to leave now. You should not plan for nor expect the British Government to be in a position to assist you to reach safety."