Authorities in Guatemala have ordered the arrest of a congressman accused of conspiring to kill three Salvadorean politicians.

The arrest warrant was issued for Manuel Castillo on Thursday after Carlos Gutierrez, the man suspected of ordering the murders, was detained near the border with El Salvador.

The charred and bullet-ridden bodies of the politicians, all members of the Guatemala-based Central American parliament, and their driver were found on February 19 last year.

Castillo "told us he didn't know [Gutierrez] but we have evidence to the contrary," Alvaro Matus, the prosecutor, said.

On Wednesday, the supreme court stripped Castillo of his immunity from prosecution.

He leaves Congress this month to become mayor of Jutiapa, the town where Gutierrez was arrested in a region police say is dominated by drug smugglers.

Neither Castillo, nor his lawyers were available to comment on the arrest warrant.

Telephone calls traced

Gutierrez was arrested on Friday after investigators traced more than 60 telephone calls between him and the suspected killers, Matus told reporters.

Shortly after the bodies were found, four Guatemalan policemen were arrested after being tracked to the scene by a satellite positioning system in their car.

The policemen were then murdered inside a maximum security prison.

Investigators had said they knew the identity of "Montana 3," a code name used by Gutierrez during his phone calls with the suspected killers, but did not publicly identify him or detain him until now.

"Montana 3" had several telephone conversations with Castillo, according to investigators.
   
"He will be transferred to the capital under heavy security," Matus said.