The South Korean government called for calm on Friday ahead of a mass rally against President Park Geun-Hye - expected to be one of the largest seen in Seoul since the pro-democracy protests of the 1980s.

Police said they were planning for around 170,000 to participate in Saturday's demonstration to demand Park step down over a corruption scandal that has left her fighting for her political life.

Organizers say they expect up to 500,000 people to turn out. "The government is concerned that the protest could lead to illegal collective action or violence," Deputy Prime Minister Lee Joon-Sik told reporters.