The Royal Navy is reported to be preparing to evacuate Britons from Libya amid escalating violence in the north African state.

Sky News reported that the survey ship HMS Enterprise is heading for the port of Tripoli and is expected to moor offshore on Sunday.

A launch protected by armed Royal Marines is expected to be sent into the port to pick up British citizens and carry them to safety on board the Plymouth-based Enterprise, which is thought to have been diverted from duties in the Mediterranean to help the rescue effort.

The Ministry of Defence (MoD) declined to comment on the reports.

An MoD spokesman said: "As the FCO (Foreign and Commonwealth Office) has made clear, the UK Government will provide assisted departure for a number of UK nationals before suspending consular operations on Monday.

"For operational reasons we will not discuss further details including whether, and in what ways, the MoD could support these efforts."

Between 100 and 300 Britons are believed to be in Libya, where fighting between rival militias has forced the UK to shut down its embassy.

Many of the consular staff were evacuated last Monday but the ambassador and core staff remained, although they will now also return to the UK.

Since the overthrow in 2011 of Colonel Muammar Gaddafi by rebels supported by British and French air strikes, the north African country has descended into a state of lawlessness as rival militias struggle for power and wealth

In the last few days, sporadic fighting between rival militias has spread northwards in capital Tripoli, including into the area where the British embassy is situated.

Tourists have been advised against all travel to the country and the Foreign Office said an assisted departure was being prepared.

Any Britons unable to take advantage of this opportunity to leave have been told they should find their way home on commercial flights, with limited departures from Misrata and Maitega airports.

On Wednesday, British Airways suspended flights to and from Tripoli up to and including Tuesday due to the security situation at the country's main international airport.

An FCO spokesman added: "Fighting has intensified in Tripoli, including around the British Embassy compounds.

"In the light of the deteriorating security situation, we are taking steps temporarily to suspend operations at the British Embassy in Tripoli after the planned assisted departure of British nationals.

"The UK Government has changed its travel advice to reflect the ongoing security situation.

"We advise against all travel to Libya and urge British nationals in Libya to leave through commercially available means.

"The British Embassy is arranging an assisted departure for British nationals. Places are limited and requests for travel will be strictly prioritised.

"We plan temporarily to suspend operations at the British Embassy following the assisted departure. We will not be able to offer consular assistance after August 4."