Police arrested 90 people as protesters for and against the controversial "Black Pete" clashed at a traditional Dutch festival for children which critics say is racist, but that many locals defend as harmless fun in the run-up to Christmas.

The event which started on Saturday in the central city of Gouda re-enacts the arrival of Saint Nicholas, bringing presents for children and helped by his sidekick Black Pete, who is invariably played by a white person with a blackened face.

"Sixty people were arrested for demonstrating in unauthorised areas, and 30 for disturbing the peace," during the procession attended by thousands and broadcast live on national television, police spokeswoman Yvette Verboon told the AFP news agency.

"Arrests were made on both sides," Verboon said amid an increasingly acrimonious and racially-charged debate in the Netherlands.

State broadcaster NOS showed images of minor scuffles breaking out on the main square, where Saint Nicholas appeared on a balcony, with protesters unfurling a large banner reading "Black Pete Racism".

Prime Minister Mark Rutte called the arrests "deeply, deeply sad".

"Everyone can talk about Black Pete's colour but you can't disturb a children's party like that," he told NOS.

Gouda mayor Milo Schoenmaker said the atmosphere had been "vicious".

"It's a pity that adults from outside the city felt the need to demonstrate among the children at the end of the procession," national news agency ANP quoted Schoenmaker as saying.

Public prosecutor spokesman Wouter Bos said all those held for demonstrating in the wrong place were anti-Black Pete protesters and they would be fined $275 each.

'Racist stereotype'

The debate around Black Pete, called Zwarte Piet in Dutch, has divided the Netherlands.

Many say that Pete - traditionally dressed in a gaudy medieval costume with a blackened face, red lips and an afro wig - is a racist stereotype dating from the colonial era.

It's a real shame that in a civilised country, in 2014, you still have to defend equality. Protester in Gouda

Black Pete's defenders say he is black from coming down the chimney and refuse to admit there might be anything racist about the historic character.

This year Saint Nicholas and dozens of Petes arrived in Gouda aboard a gift-filled boat from Spain in a national event looked forward to by children.

For the first time, the mayor introduced other coloured Petes, angering many.

They include "Cheese Petes" with yellow faces, "Stroopwafel Petes" with striped, light brown faces resembling the traditional Dutch syrup biscuit of the same name and a white-faced "Clown Pete".

Nevertheless, protesters attended Saturday's annual procession wearing T-shirts reading "Black Pete Colonial Symbol" or "Black Pete Doesn't Fit".

"Some black kids feel hurt at this time of year," said a man at the procession who gave his name as Knoledge.

"It's a real shame that in a civilised country, in 2014, you still have to defend equality," he told AFP.

"If we were seen as equals, Black Pete would have been changed a long time ago so that this celebration is for all Dutch people," he said.

At a press conference after the procession, the man playing the role of Saint Nicholas was asked if he had followed the Black Pete debate.

"It will all work itself out," he said. "Nobody should be worried."