Czech Prime Minister Petr Necas announced on Sunday that he will resign on Monday after days of political turmoil.
The ruling coalition will try to form a new government led by someone nominated by his Civic Democratic Party.
The BBC reports pressure had been growing on Mr Necas to quit since prosecutors charged his closest aide, Jana Nagyova, with corruption and abuse of power.
Armed police carried out raids on government and private offices on Wednesday night.
Two former MPs, an ex-minister and the current and former heads of military intelligence have also been detained.
Ms Nagyova is suspected of bribing the former MPs with offers of posts in state-owned firms.