'Santa protest' against South Korea President Park Geun-hye

Tens of thousands of South Koreans have marched through the streets of Seoul - many dressed as Santa Claus - calling for the immediate removal of their president.

The festive protest marks the ninth week of rallies against Park Geun-hye.

Parliament has voted to impeach Ms Park over a corruption scandal, but that decision has to be confirmed by South Korea's constitutional court.

The demonstrators want her to resign at once.

Organisers say more than 550,000 people joined the ranks marching towards the presidential Blue House, the prime minister's office and the constitutional court. Police figures were not available.

The crowd chanted "Arrest Park immediately!" and sang along to Christmas songs whose lyrics they had changed to mock Ms Park.

"This is a special Christmas Eve as it gives me a chance to show my children what democracy is all about", Yoon Ki-Seung told the AFP news agency, as his son and daughter held up banners.

Park Chans, a 25-year-old office worker in a Santa costume, said the aim was to ensure those accused of corruption are held accountable.

"I hope that in the new year, this country will be a better place to live for the youth," he said.

Between 200 and 300 young people in Santa outfits handed out books and Christmas cards to children at the demonstration, chanting: "Gifts to children and handcuffs to Park!"

The scandal which has engulfed Ms Park centres on her relationship with a long-time friend, Choi Soon-sil, who faces charges of coercion and abuse of power.

It is alleged that after Ms Park became president in 2013, Ms Choi, 60, used their friendship to pressure top firms into donating to foundations she controlled, and then siphoned off funds for her own gain.

Prosecutors are also investigating new allegations that Ms Choi sent dubious assets worth hundreds of millions of dollars overseas.

The president's one-time ally has been in custody since October, and was brought to a special prosecutors' office to be questioned on Saturday.

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"We will question her to confirm her earlier statements and investigate other allegations," a spokesman for the special prosecutor told reporters.

Ms Park has been suspended from her duties since the impeachment vote on 9 December, but insists she will wait "calmly" until the constitutional court delivers its decision.

If it confirms her impeachment, she will be permanently removed from office, and elections will be held within 60 days.