PARIS — Prime Minister Petr Necas of the Czech Republic said Sunday that he would resign, following a corruption scandal involving a senior aide. The resignation, which he said he would submit Monday, plunged the country into a period of political uncertainty.

Speaking at a news conference in Prague, the Czech capital, Mr. Necas said he would also resign as chairman of his party, the center-right Civic Democrats.

On Friday, Czech prosecutors said they had charged several people, including Jana Nagyova, the prime minister’s chief of staff, and the current and former heads of military intelligence, in the most extensive anticorruption operation since the end of Communism. Ms. Nagyova was charged with abuse of power and bribery after prosecutors said she ordered a military intelligence agency to spy on three people. The Czech news media reported that they included Mr. Necas’s wife, Radka Necasova. Mr. Necas said last week that he and his wife were divorcing.

Mr. Necas had initially reacted to the scandal with defiance, saying that he had nothing to do with any illegal surveillance operation and that he would not step down. But analysts said that having so close an aide ensnared in the scandal made it untenable for him to stay on. The opposition planned a vote of no confidence in Parliament on Tuesday, and it was unclear whether he could retain the backing of his coalition partners.