They were arrested on Thursday after images emerged of people appearing to imitate sex acts at a party in a villa in Siem Reap in the north-west.
If convicted, they could face up to a year in prison.
Also among those arrested are citizens of Canada, New Zealand, the Netherlands and Norway, reports say.
However several people in the pictures from the party do not appear among those held, reports say.
Britain's Foreign Office said it was providing assistance to the arrested UK nationals.