Some of those involved in the assassination of Iran`s top nuclear scientist last month have been arrested, an adviser to the Iranian parliament speaker said on Tuesday, according to the semi-official news agency ISNA.

Iran has blamed Israel for the November 27 killing of Mohsen Fakhrizadeh, who was seen by Western intelligence services as the mastermind of a covert Iranian nuclear weapons programme. Tehran has long denied any such ambition. Israel has neither confirmed nor denied responsibility for the killing.

The perpetrators of this assassination, some of whom have been identified and even arrested by the security services, will not escape justice,” ISNA quoted adviser Hossein Amir-Abdollahian as telling Iran`s Arabic-language Al Alam TV.

“Were the Zionists (Israel) able to do this alone and without the cooperation of, for example, the American (intelligence) service or another service? They certainly could not do that,” Amir-Abdollahian said.

Iran has given contradictory details of Fakhrizadeh`s death in a daytime Nov. 27 ambush on his car on a highway near the capital Tehran. A senior Revolutionary Guards commander has said the killing was carried out remotely with artificial intelligence and a machine gun equipped with a “satellite-controlled smart system”

Witnesses earlier told state television that a truck had exploded before a group of gunmen opened fire on Fakhrizadeh`s car. Experts and officials told Reuters last week that Fakhrizadeh`s killing exposed security gaps that suggest Iran`s security forces may have been infiltrated and that the Islamic Republic is vulnerable to further attacks.