A Russian rights group said Chechen authorities on Thursday abducted a human rights advocate in Moscow who has been critical of Chechnya's Kremlin-backed leader.

Arbi Khachukayev was detained by Chechen security officers and was flown to the Chechen capital of Grozny against his will, the Memorial group said. It said it learned about his abduction when he was being taken to the Vnukovo airport outside Moscow.

Khachukayev heads a Chechen rights group named Law that has exposed alleged human rights abuses committed by forces loyal to Chechen President Ramzan Kadyrov.

The Chechen Interior Ministry said Khachukayev was detained for alleged involvement in an armed assault, the RIA-Novosti news agency reported.

A string of Kadyrov's critics and political rivals have been brutally murdered in recent years in Russia, Austria and Dubai. This year alone, two human rights advocates have been abducted in Chechnya and killed contract-style.

Kadyrov has denied accusations of being behind the killings.

Rights groups claim that Kadyrov's forces are responsible for abductions, torture and extrajudicial killings of people suspected of ties to Islamic militants.

Kadyrov's critics say that, by backing him, Moscow has created a climate that encourages unchecked brutality. But the Kremlin has stonewalled the criticism and praised Kadyrov for pacifying the southern Russian region.

Chechen separatists battled Russian troops and pro-Moscow Chechen forces through two wars after the 1991 Soviet collapse.