Thousands of South Koreans are protesting in the capital Seoul to demand President Park Geun-Hye's resignation due to corruption allegations.

Some 40,000 demonstrators are expected to turn out in central Seoul for a rally supervised by 20,000 police officers. Police have banned protesters from marching through the streets, citing traffic concerns. It's possible demonstrators will try to make their way to the presidential Blue House.

Park has issued a televised apology over the influence-peddling scandal involving her long-time confidant Choi Soon-Sil. The president took the blame but denied having links to a religious cult. She has also agreed to be questioned in a formal corruption probe. Park's approval rating crashed to just five percent this week, the lowest-ever rating for a sitting South Korean president.