MPs and human rights groups have criticised the Metropolitan Police after 52 people were arrested in London on the day of the Coronation.

Among those held was the head of the group Republic, which wants to scrap the monarchy and elect a head of state.

Graham Smith, who was released on Saturday evening after 16 hours in custody, said there was "no longer a right to peaceful protest in the UK".

Scotland Yard said it had acted "in a proportionate manner".

Commander Karen Findlay defended her officers' response to protests during the day of the Coronation, saying they had a duty to intervene "when protest becomes criminal and may cause serious disruption".

She added that the Coronation was a "once in a generation event and that is a key consideration in our assessment".

Hundreds of protesters gathered in the rain in central London on Saturday, with chants including "down with the Crown", "don't talk to the police" and "get a real job".

Other protests were organised in Cardiff, Glasgow and Edinburgh. No arrests were reported outside London.

Scotland Yard said those arrested had been held on suspicion of affray, public order offences, breach of the peace and conspiracy to cause a public nuisance around the coronation.

While campaigners insisted their protests were peaceful the police said they had intelligence that groups were "determined to disrupt" the occasion.

Several Labour MPs criticised the Met's response, with senior backbencher Sir Chris Bryant writing on Twitter that "freedom of speech is the silver thread that runs through a parliamentary constitutional monarchy".

Shadow minister Jess Philips also used social media to say that "our nation and our King is not so fragile as to not be able to take harmless protest of a different view".

Labour MP Richard Burgon said he was ''deeply concerned" by the arrests, while MP Zarah Sultana said: "Whatever you think of the monarchy, the right to peaceful protest is fundamental to democracy."

Among those critical of the Met was the UK director of Human Rights Watch, Yasmine Ahmed, who likened its actions to "something you would expect to see in Moscow, not London".

The King and Queen went past some of the protesters as they travelled in the Diamond Jubilee State Coach towards Westminster Abbey

Mr Smith confirmed he was released late on Saturday evening, adding that other members of Republic were still in custody.

Writing on Twitter he said there was "no longer a right to peaceful protest in the UK".

"I have been told many times the monarch is there to defend our freedoms. Now our freedoms are under attack in his name."

Mr Smith was arrested early on Saturday - before the Coronation began - at a protest in Trafalgar Square.

Footage during the day showed several protesters wearing "Not My King" T-shirts being detained - including Mr Smith.

Republic also said hundreds of its placards had been seized by police.

The Met said it had confiscated "lock-on devices" - which protesters can use to secure themselves to things like railings.

It has now become illegal to prepare to lock-on following changes to the law that were passed this week.

But Matt Turnbull, another member of Republic who was arrested, said the straps being used to hold the placards had been "misconstrued" as lock-on devices.

Elsewhere on Saturday, climate activist group Just Stop Oil said about 13 protesters were arrested on The Mall in central London along with five others in Downing Street.

A Just Stop Oil spokeswoman said their plan was "only to display T-shirts and flags", adding: "This is a dystopian nightmare."

Concerns about the police's approach to the Coronation were also raised by Westminster City Council's cabinet member for communities and public protection over reports that volunteers with its Night Star programme had been arrested while handing out rape alarms.

Councillor Aicha Less said the authority was "working with the Metropolitan Police to establish exactly what happened" and was "in touch with our volunteers to ensure they are receiving the support they need". (BBC)

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