MOSCOW (AFP) -- Russian security services raided the homes of several Jehovah's Witnesses in Moscow on Wednesday, in an ongoing crackdown on the US-based religious movement.

Moscow outlawed the Jehovah's Witnesses in 2017, labelling it an extremist organisation and has since sentenced several members to lengthy jail terms.

The Investigative Committee, which probes major crimes, said on Wednesday several  "organisers and members" had been detained.

Prosecutors, the FSB security services and the national guard carried out searches at 16 addresses, the committee said.

Investigators said the Jehovah's Witnesses had established a branch in the capital where "secret meetings" were convened to study "religious literature."

Founded in the United States in the late 19th century, the religious movement has been repeatedly accused of refusing to respect state symbols such as flags.

Although President Vladimir Putin said in 2018 its members should not be considered terrorists, Moscow has continued bringing legal action against the group.

The Russia Orthodox Church has spoken out against the movement with one official describing it as a "destructive sect."

Investigators raided addresses in more than 20 regions across the country last November in another probe into the group.