Members of a Russian rock band critical of the war in Ukraine are facing possible deportation home from Thailand after they were arrested in Phuket for working without a permit, officials told Reuters on Monday.

Human rights activists fear the self-exiled rock band Bi-2 would face harsh punishment if it was sent back to Moscow. The group is known for its condemnation of Russia's invasion of Ukraine, with its lead singer Igor Bortnick labelled by Russian authorities as a "foreign agent" after he criticised President Vladimir Putin online.

Seven band members were detained at Bangkok's immigration detention centre after their arrests on Jan 24 for working without a permit, Phuket's Immigration Bureau told Reuters.

Sunai Phasuk, a senior researcher on Thailand for Human Rights Watch, said the band members would "likely face harsh prosecution and other grave dangers" if they were sent back to Russia.

Other officials told Reuters that the band members could seek an alternative destination if they felt unsafe to return to Russia.

Band members with dual citizenship have the option of choosing any other country that they belong to as a country of origin, one official said.

Some band members have dual citizenship with Israel and Australia, the two places the band were based before they moved to Russia in 1999.