(CNN) -

Bilal Bettamer is a 23-year-old student who wants to save Benghazi from those he calls "extremely dangerous people." But his campaign against the criminal and extremist groups that plague the city has put his life at risk, and he says that if he receives more threats, he will have to leave Libya.

Libya can't afford to lose the likes of Bettamer. A law graduate and civil activist, he helped organize the protest against jihadist groups after the attack on the U.S. Consulate there in September, in which four Americans were killed.

That protest led to the expulsion from Benghazi of the militant Ansar al-Sharia group -- whose members were suspected of involvement in the attack -- and other jihadists from the city.

A month later, Bettamer says, the extremists were back in Benghazi with a vengeance. He estimates there are maybe 100 of them at large. And last week, several European governments, as well as Canada and Australia, urged their citizens to leave this eastern Libyan city immediately, with Britain speaking of an "imminent threat."

One Libyan source with contacts in Western intelligence circles says the warning followed an intercepted communication that revealed a specific and concrete plan to attack British interests.

Fighting a ghost

Bettamer says Ansar al Sharia has expelled its more militant members and is now helping provide security at the western entrance to Benghazi.

"People describe every extremist now as Ansar al Shariah, [but] there are people more extreme and more dangerous," he says.

Bettamer says he received three hostile text messages after the Save Benghazi Friday protest.

"You feel the threat and feel you are being watched; they follow you and you feel something abnormal."

A "religious-looking man" had approached Bettamer's uncle outside their family home in Benghazi with a message for Bilal: "Tell him to watch out." The trouble is, no one knows who the assailants are.

"It's like fighting a ghost," Bettamer says.

Bettamer says police and security forces are gradually getting better and that ordinary people in Benghazi are relatively safe. That's not so for activists or members of the security forces, who are often targeted for assassination.

The past three months have seen several assassinations, bombings and kidnappings of police and security officials in Benghazi. Among them was the abduction earlier this month of the head of the criminal investigation division, Abdel Salam al-Mehdawi. He'd been investigating the murder of Benghazi's chief of police in October and is still missing.

Last week, Naji El-Hariri, the nephew of a leading figure in the Libyan revolution, was shot in Benghazi's Al Laithi neighborhood, where a senior police officer was killed a week earlier by a bomb.

And earlier this month, gunmen ambushed the car of the Italian consul in Benghazi, Guido De Sanctis. He escaped injury, but the Italians suspended their diplomatic presence.

State of denial

Outgoing U.S. Secretary of State Hillary Clinton told a congressional hearing last week that the new Libyan government had the "willingness but not the capacity" to provide security.

Bettamer doesn't agree, saying the government is in a state of denial.

"The government is ignoring the problem and not confronting it," he says, by blaming everything on Moammar Gadhafi loyalists. He believes it's afraid of confronting extremist groups.

Another Libyan source familiar with the situation in Benghazi agreed.

"When every day you have campaign of assassinations and attacks against government, police and security facilities and nobody is arrested, you have a bad situation," the source said, adding that a group affiliated with Ansar al Shariah now controls one of the largest Gadhafi-era military camps in the city.

Libyan Interior Minister Ashur Shuwail unveiled a plan last week involving the police, army and some militia to secure Benghazi -- one that may involve a nightly curfew from midnight to 5 a.m.

But it's not just Benghazi. The UK Foreign Office has advised against travel throughout Libya -- apart for Tripoli and a number of towns on the coast. To the east of Benghazi, several towns are jihadist strongholds.

Canada's Foreign Affairs Department warned last week of "ongoing clashes, including indiscriminate shelling, between pro-government militia and Gadhafi loyalists in Bani Walid," as well as clashes between armed groups in Sabha and Kufra in the south. An estimated 400 people have been killed in tribal clashes around Kufra over the past year.