Thailand has revoked the passport of fugitive former premier Thaksin Shinawatra for allegedly inciting the protests that sank the East Asia Summit last week.
A government spokesperson says that the foreign ministry can cancel or recall a passport if it can prove that a person has caused damage to the country.
Ousted in a military coup in 2006, Mr Thaksin lives in exile in order to avoid serving a two-year sentence for a corruption conviction.
In recent weeks he has made a series of speeches to his supporters in Thailand by videolink and phone
There are already arrest warrants out for him and 13 of his key supporters - members of the United Front for Democracy against Dictatorship - for violating state-of-emergency regulations.
All quiet for now, but redshirts have vowed to return
A state of emergency remained in the Thai capital, Bangkok, for a fourth day on Wednesday, with security forces still tightly guarding the area around the prime minister's office, the epicentre of protest action over the past three weeks.
Few people believe, however, that the end of this round of protests heralds a return to stability in Thai politics.
Prime minister Abhisit Vejjajiva's position has been strengthened, but opposition to him remains strong and the "red shirt" protesters have vowed to return, even though some of their leaders have been arrested.
Thailand's seemingly intractable political divide broadly pits royalists, the military and the urban middle class against the rural poor loyal to Mr Thaksin.