Two Australians have been told to leave the eastern Libyan city of Benghazi as soon as they can due to a "specific and imminent threat" against Westerners.

The Department of Foreign Affairs and Trade (DFAT) issued a travel alert on Friday morning following similar warnings from Britain, Germany and the Netherlands, describing the threat as specific and imminent.

"All Australians in Benghazi should leave immediately," DFAT said on its website.

A spokeswoman for DFAT says Australia's embassy in Rome has contacted the two Australians who are registered as being in Benghazi, telling them the city is "not the best place to be".

The department earlier reminded Australians its travel advisory for Libya was still at its highest "do not travel" level "due to the high threat of terrorist attack, the ongoing threat of kidnapping and the unpredictable security situation throughout the country".

"Australians who choose to remain in Libya should ensure that they have appropriate personal security measures in place," DFAT said.

There are 22 Australians registered as being in Libya.

The warning comes a day after US Secretary of State Hillary Clinton testified to Congress about the September attack on the US diplomatic mission in Benghazi that killed four Americans, including the ambassador to Libya.

It also comes as French troops battle al-Qaeda-linked militants in Mali, and follow the deaths of dozens of foreigners taken hostage by Islamist extremists in Algeria - though it remains unclear if those two events are linked to the new Benghazi concerns.