— South Korean prosecutors on Sunday said they believe President Park Geun-hye conspired in the criminal activities of a confidante who allegedly manipulated government affairs and exploited her presidential ties to amass an illicit fortune — a damning revelation that may convince opposition parties to push for Park’s impeachment.

Prosecutors are planning to question Park, who has immunity but can be investigated, said Lee Young-ryeol, chief of the Seoul Central Prosecutors’ Office.

Prosecutors on Sunday formally charged Park’s longtime friend Choi Soon-sil on suspicion of interfering with state affairs and bullying companies into giving tens of millions of dollars to foundations she controlled.

Lee said at a news conference that evidence showed “the president was involved as a conspirator in a considerable part of the criminal activities by suspects Choi Soon-sil, Ahn Jong-beom and Jung Ho-sung,” referring to two presidential aides charged Sunday with helping Choi.

Park faces growing calls to resign over the scandal, which critics say is undermining Korea’s democracy.

On Saturday, police said about 170,000 people turned out for an anti-Park protest near Seoul’s City Hall. Some also marched near the presidential offices.

— Associated Press