The warnings come a day after U.S. Secretary of State Hillary Rodham Clinton testified to Congress about the deadly September attack on the U.S. consulate in Benghazi that killed four Americans, including the ambassador to Libya. They also come as French troops battle al-Qaida linked militants in Mali, and follow the deaths of dozens of foreigners at the hands of Islamist extremists in Algeria — though it remained unclear if those two events were linked to the European nations' concerns about Libya.

The foreign ministries of the three countries issued statements variously describing the threat as specific and imminent but none gave details as to its exact nature. Germany and Britain urged their nationals still in Benghazi to leave "immediately" while Dutch Foreign Ministry spokesman Thijs van Son said that "staying in this area is not to be advised."

It was not immediately clear how many people could be affected; Britain's Foreign Office said likely "dozens" of its citizens were in the city, while Dutch Foreign Ministry spokesman Thijs van Son said there are four Dutch citizens registered as being in Benghazi and possibly two more. Several countries have for months advised against all travel to the city, especially after the U.S. consulate was attacked, and local residents said that many foreigners had already left in recent weeks.

Benghazi, a city of 1 million people, is a business hub where many major firms employ Westerners. It also was where the Libyan uprising against longtime dictator Moammar Gadhafi began in 2011. Gadhafi was eventually toppled and killed after NATO backed the rebel movement, and the Arab country has since struggled with security. Al-Qaida-linked militants operate in the country alongside other Islamist groups.

Adel Mansouri, principal of the International School of Benghazi, said British and foreign nationals were warned two days ago about a possible threat to Westerners.

He said the school's teachers were given the option of leaving but decided to stay. The school has some 540 students. Most are Libyan with some 40 percent who hold dual nationality. Less than 5 percent are British while 10 to 15 students have U.S.-Libyan nationality, Mansouri said. Classes were not due to resume until Sunday because of a holiday Thursday.

"We told the British ambassador we are staying, and we'll be in touch," said Mansouri, himself a Libyan-British dual national. "We don't see a threat on the ground."

Saleh Gawdat, a Benghazi lawmaker, said French doctors who were working in Benghazi hospitals have left the city and that the French cultural center has closed out of concerns about potential retaliation over the French-led military intervention in nearby Mali, which began two weeks ago.

Violence in Benghazi has targeted both foreigners as well as Libyan officials in recent months — with assassinations, bombings and other attacks.

In addition to the Sept. 11 attack on the U.S. consulate, an Italian diplomat's car was fired on by militants in Benghazi. The consul, Guido De Sanctis, wasn't injured in the attack earlier this month, but the incident prompted Italy to order the temporary suspension of its consular activities in the city and send its foreign staff home.

Islamist extremists are often blamed for targeting security officials who worked under Gadhafi, as a kind of revenge for torturing or imprisoning them in the past. Many city residents also blame Gadhafi loyalists who they say are trying to undermine Libya's new leaders by sowing violence.

Ibrahim Sahd, a Benghazi-based lawmaker and politician, said that the new government is putting together a plan to beef up security in the city and this "might have worried the Westerners of a backlash."

Noman Benotman, a former Libyan jihadist with links to al-Qaida who is now an analyst at London's Quilliam Foundation, said other groups inspired by the terror network have been gaining a following since Gadhafi's fall. There have been nearly a dozen attacks against Western targets in Libya recently, he said.

"It's the same al-Qaida ideology that is driving these militants," Benotman said.

He added, however, that the militants were unlikely to target oil or gas installations in Libya because they need support from the population. "Targeting these installations would turn Libyan workers and tribes against them," he said.

Oil companies working in other parts of Libya said they were aware of government warnings to citizens but there were no immediate plans for evacuations.