The director of Greece's competition watchdog has been remanded in custody pending trial on extortion and blackmail charges.
Mr Adamopoulos is alleged to have demanded cash bribes
In one of the country's biggest corruption cases, Panayotis Adamopoulos is charged with demanding a 2.5m euros ($3.18m; £1.6bn) bribe from a company.
The case is being closely watched in Greece as Mr Adamopoulos has close ties with the ruling New Democracy party.
Currently suspended from duty, he denies any wrongdoing.
The arrest of Mr Adamopoulos and two alleged accomplices, a customs officer and a trader, comes as Greek Prime Minister Costas Karamanlis said in a speech that his government would crack down on corruption.
Mr Karamanlis and his ruling right-wing party have been in government since March 2004.
Greece is ranked the most corrupt country in the 12-nation eurozone area by global anti-corruption watchdog Transparency International.