SEOUL, South Korea — Tens of thousands of South Koreans poured into the streets of downtown Seoul on Saturday to demand that President Park Geun-hye step down amid a political scandal.

The protest, the largest anti-government demonstration in the capital in nearly a year, came a day after Park apologized on live television amid rising suspicion that she allowed a confidante to manipulate power from the shadows.

Last week, prosecutors arrested Choi Soon-silz over allegations businesses were pressured into giving $70 million to two foundations.