Britain, Germany, the Netherlands and Australia have all urged their citizens to leave the Libyan city of Benghazi due to a "specific, imminent threat to Westerners", linked to French action in Mali.

Britain's warning on Thursday sparked an angry response from Libya's government, which said there was "no new intelligence" to justify such concerns in the eastern city.

Passengers wait to board a plane at Benghazi's Benina international airport after warnings from European countries urging their nationals to leave the eastern Libyan city of Benghazi, Jan 24, 2013. Britain cited a "specific and imminent" threat to Westerners days after a deadly attack by Islamist militants in neighbouring Algeria. [Photo/Agencies]

But Australia's department of foreign affairs said on Friday: "We are aware of a specific, imminent threat to Westerners in Benghazi. All Australians in Benghazi should leave immediately.

"There is a risk of retaliatory attacks against Western targets in Libya following the French intervention in the conflict in Mali in January 2013."

Benghazi was the cradle of the uprising that ousted dictator Muammar Gadhafi in 2011 and also the city where a US ambassador was killed in an attack in September.

The initial alert from London came hours after British Prime Minister David Cameron warned that last week's deadly attack on a gas complex in Algeria was only one part of what would be a "long struggle" against terrorists around the world.

In a speech at the World Economic Forum in Davos, Cameron told delegates: "I believe we are in the middle of a long struggle against murderous terrorists and the poisonous ideology that supports them."

The Foreign Office in London said in a statement: "We are now aware of a specific and imminent threat to Westerners in Benghazi, and urge any British nationals who remain there against our advice to leave immediately."

Later on Thursday, both Germany and the Netherlands also warned their citizens to leave.

Abdullah Massoud, Libya's deputy interior minister, expressed "astonishment" at the warnings, and said Tripoli would be demanding an explanation.

"We acknowledge that there are security problems in Benghazi and that there have been for several months, but there is no new intelligence that could justify this reaction from London," he said.

"On the contrary. We are now in the process of establishing our authority in the east and in all of Libya, and the security forces are organizing themselves little by little and are more and more visible on the ground."

Since its pivotal role as the springboard for the uprising, Benghazi has emerged as a hub for jihadist groups.

On Wednesday, US Secretary of State Hillary Clinton warned of the challenge in testimony to Congress about September's attack on the US mission in Benghazi.

US Ambassador Chris Stevens and three other US citizens were killed when dozens of heavily armed militants linked to al-Qaida overran the compound and a nearby CIA-run annex.

Britain closed its mission in Benghazi around the same time and updated its official advice to warn against traveling there and to most of Libya. The number of Britons currently in Benghazi is only thought to be in the dozens.

Earlier this month the Italian consul in Benghazi was shot at in his car, although he escaped unhurt.

Last week's attack on the BP-run In Amenas gas plant in Algeria, in which at least 37 foreign hostages and one Algerian hostage were killed, sparked fresh concerns about rising Islamist extremism across North Africa.

Agence France-Presse