Relatives say the 18-year-old son of a former police colonel who joined Islamic State (IS) extremist group has been arrested, according to Radio Liberty’s Tajik Service.

Behrouz Gulmorodov's relatives told RFE/RL’s Tajik Service on April 17 that he was detained three weeks ago and is being held incommunicado.

They said they have received no explanation of the arrest, which could not be independently verified.

Behrouz Gulmorodov's father, Colonel Gulmurod Halimov, was commander of the Tajik special police unit, known as OMON.

He went missing in April 2015 and later appeared on the Internet, saying he had joined the IS group.

Last August, the U.S. State Department called Halimov a key member of the IS extremist group and offered a $3 million reward for information on his whereabouts.

Western media reports quoted Iraqi officials on April 14 as saying that Halimov was killed in an air strike in Mosul.

Meanwhile, the Interior Ministry of Tajikistan has denied information about the arrest of Halimov’s son Behrouz in Tajikistan as baseless.