PARIS — The Czech Republic’s governing party began jockeying to form a new government on Monday after the prime minister, Petr Necas, resigned over an espionage and bribery scandal that has plunged the country into political instability.

His resignation came just days after an organized crime unit began the most extensive anti-corruption operation since the end of Communist rule in 1989.

In nationwide raids, officers wearing black face masks arrested several officials with links to Mr. Necas, and seized $8 million in cash, tranches of documents and quantities of gold.

Mr. Necas had come under pressure to resign after his chief of staff, Jana Nagyova, was charged Friday with abuse of power and bribery. Prosecutors and the police said she had ordered the intelligence services to spy on three people, including Mr. Necas’s wife, whom he is divorcing. The police said they were shocked when wiretaps of Ms. Nagyova’s phone showed that she had used the secret services for personal motives.