JERUSALEM (AP) _ The government is investigating whether private security companies from Israel helped train assassination squads for Colombian drug lords, a Foreign Ministry official said Saturday.

An Israeli reserve officer whom news reports have linked to such activities said he had actually been teaching cattlemen how to protect themselves from communist guerrillas.

Deputy Foreign Minister Benjamin Netanyahu, speaking on Israel radio, said Israel had set up a special investigating committee without being requested to do so by either Colombia or the United States.

Colombia and the United States launched a major drive to break up the drug- trafficking underworld in Colombia after drug bosses there had a presidential candidate killed last week.

The Medellin drug cartel supplies most of the cocaine sold in the United States.

''Two days ago, we asked the Colombian government at the request of Foreign Minister (Moshe) Arens for any information available to them, and we have offered them assistance with anything we can do,'' Netanyahu said.

''We need to find out if Israelis indeed are involved ... and what we can do to make sure that they are not,'' he added.

The Israeli government made the request after American news reports that some Israelis were helping Colombian drug cartels train assassination squads.

The Foreign Ministry official said Israel would take action against anyone found to have violated Israeli laws.

He had said Friday that Israel may revoke passports of any Israeli mercenaries proven to be involved in training assassination squads.

Lt. Col. Yair Klein, identified as an Israeli trainer of such squads on the basis of videotape broadcast by the NBC News, returned to Israel on Friday from Miami.

The 44-year-old Israeli is a retired commander of a paratroop anti-terror unit and president of a private security firm called Spearhead.

''I trained a group of farmers who defended themselves against terrorist organizations, mostly the group called M-19, a guerrilla group with the goal of turning Colombia into Cuba or Nicaragua,'' Klein said on Israeli television Friday.

A senior Defense Ministry official said Klein is likely to be questioned about his activities in Colombia. The television said that the ministry is considering filing a police complaint.

However, Israeli television and major dailies last week identified Klein as the leader of four Israeli army reserve colonels reported to have worked with the Colombian drug traffickers.

Klein said Saturday on armed forces radio that his company trained Colombian cattlemen and that the video in which he was shown was made by Spearhead for advertising purposes.

He said the company completed its training a year ago and that his last visit to Colombia was four months ago. Klein said that visit had nothing to do with the training program, but he did not say exactly why he went.