Bogota, Aug 25 (IANS/EFE): Around 90 teenagers in Puerto Asis town in Colombia have received death threats on social networking website Facebook, which has prompted several families to flee, officials said.

The first death list appeared after the Aug 15 murders of two of the young people threatened, Andres Gerardo Verdugo, a local official said.

Two more lists have followed, he said, with the latest appearing Monday.

"The worried parents have begun to take their children out of the town," he said, adding that authorities have boosted security in Puerto Asis and are investigating the threats.

Besides the deaths lists, posters threatening members of the municipal police force also began circulating during the weekend, he said.

The national police have launched "a great operation to give protection" to the targets of the threats, Gen. Oscar Naranjo, a senior official, said Tuesday.

Police is also probing threats against some 60 other people in Putumayo, Nariño, Antioquia and Cundinamarca, the general said.

The threats, which have prompted some residents to leave, are part of a strategy by new drug trafficking gangs to gain control of key territories, officials said.