Willie Frazer is expected to appear in court today after being arrested in Portadown for allegedly taking part in a protest at the Maze prison.
The Loyalist campaigner was arrested at about 7.35pm last night on suspicion of breaching his bail conditions.
He is currently on bail over union flag protest charges, which include encouraging offences by an address to demonstrators in January.
The Maze protest on Monday was organised by victims' group FAIR (Families Acting for Innocent Relatives) against the plans to build a peace centre on the site.
Frazer's bail conditions ban him from being within two miles of a public protest or procession.