European Governments Urge Their Citizens to Leave Benghazi

LONDON--Several European governments urged their citizens to leave the Eastern Libyan city of Benghazi in response to what they described as "an imminent threat to Westerners," a move that highlights jitters in the region on the heels of last week's deadly hostage crisis in Algeria.

The U.K. foreign office said in a statement it is "now aware of a specific and imminent threat to Westerners in Benghazi." The U.K., like the U.S., had advised its nationals against all travel to Benghazi since the September 2012 assaults on U.S. government posts. The U.K. foreign office in its alert Thursday said it advised any who remain to "leave immediately."

Germany and the Netherlands later Thursday also urged their citizens to leave the Libyan city.

The warnings come the day after U.S. Secretary of State Hillary Rodham Clinton testified in a congressional appearance about the deadly September 2012 attack on the U.S. consulate in Benghazi that killed four Americans, including the ambassador to Libya. Following the September attack, the U.S. evacuated all government officials and contractors from the city.

The warnings Thursday follow the deaths of dozens of foreigners during a siege of a natural-gas plant in Algeria by Islamist extremists and come as French troops fight al Qaeda affiliates in Mali.

The U.K.'s warning Thursday said the threat was to Westerners in Benghazi but didn't provide further detail as to the nature of the threat.

A British government source said the threat appeared to be Islamic extremist-related but declined to give more specific details. The person added that the British government knows that al Qaeda in the Islamic Maghreb, or AQIM, uses Northern Mali as an operating base and has the proven capability of traveling long distances to carry out attacks.

AQIM and related groups have spread across a territory that encompasses parts of Mali, Algeria, Libya and Chad. There are a range of groupings and criminal gangs in the area that carry out a range of acts from terrorist attacks to kidnappings for financial reward.

Since 2008, AQIM and related groups have taken more than 25 hostages of a variety of nationalities, primarily European, according to the British government. A British citizen was among a group of tourists who were kidnapped in Mali in January 2009 and was killed some months later.

The warning about Benghazi, which hosts the offices of many foreign oil-services companies, comes after the Libya government said Wednesday it was boosting security at its oil fields in response to the Algerian attack. That assault, on a facility operated by BP PLC (BP.LN, BP), Statoil ASA (STL.OS, STO) and Algerian state oil company Sonatrach, left at least 37 foreign workers dead.

Several regional experts have highlighted Libya's oil industry--where oil giants such as the U.K's BP, U.S.-based ConocoPhillips (COP) and Italy's Eni SpA (ENI.MI, E) operate--as one of the most likely targets of a terrorist attack following the Algerian incident. Many of the country's oil and gas exploration and production sites are located in the sparsely populated deserts of Western Libya, not far from the Algerian border. And following the toppling of former dictator Moammar Gadhafi in 2011, experts say Libya suffers from lax security.

--Benoit Faucon, Margaret Coker, Siobhan Gorman and Laura Stevens contributed to this article.