Anti-monarchy protesters should not "ruin" the Queen's funeral or lying-in-state for mourners, Keir Starmer has said.
Speaking on Wednesday the Labour leader said protesters should show "respect" for people who had made a "huge effort" to wait in line.
Sir Keir said protest was a "great British tradition" but that hundreds of thousands of people wanted to have a "moment" with the Queen.
It comes after criticism of examples of heavy-handed policing of peaceful anti-monarchy protesters around the country drew criticism from civil liberties campaigners.
Sir Keir said the country's response to the death of the Queen had been "very moving" and that it had been an "incredible moment" for the country.
He was speaking ahead of the Queen's coffin being moved to Westminster Hall this afternoon, accompanied by the King and other members of the royal family.
Members of the public will be able to view the coffin to pay their respects from 5pm, with Westminster Hall open 24 hours a day until the morning of 19 September.
Speaking on BBC Breakfast Sir Keir was asked about the right protest, and said: "The word I'd use around that issue is respect.
"I think if people have spent a long time waiting to come forward to have that moment as the coffin goes past or whatever it may be, I think respect that, because people have made a huge effort to come and have that private moment to say thank you to Queen Elizabeth II.
"Obviously we have to respect the fact that some people disagree. One of the great British traditions is the ability to protest and to disagree, but I think if it can be done in the spirit of respect.
"Respect the fact that hundreds of thousands of people do want to come forward and have that moment, don't ruin it for them."
He added that he would return to Westminster Hall later with his family to privately pay his respects to the late monarch.
"Today I'll be there as part of the reception committee to receive the coffin," he said.
"Then later on this evening in a private capacity, because my wife and our children... they want to come in, and as a family we will then pay our own personal respects to a remarkable sovereign."
His comments come after reports that Labour MPs were emailed by Sir Starmer’s office and told not to publicly talk about anything other than the Queen. In emails apparently sent by the leader’s office, MPs were ordered not to do “any media, except for your own tribute to local outlets”.
The Labour leader’s emphasis contrasts with civil liberties campaigners and others, who have expressed alarm about the police response to anti-monarchy protesters, including the heckling of Prince Andrew in Edinburgh and a barrister holding a blank sign in London.
Former Tory Cabinet minister David Davis on Wednesday wrote to the Chief Constable of Police Scotland yesterday expressing concern that demonstrators had been charged by police.
Mr Davis said he was writing a "strong monarchist" who "nevertheless" hoped that "members of the public will remain free to share their opinions and protest in regard to issues about which they feel strongly".
Meanwhile Liberal Democrat home affairs spokesperson Alastair Carmichael said that while he disagreed with protesters, in an open and democratic society they “must have the right to express their views peacefully”.
And Labour MP Zarah Sultana said: “No one should be arrested for just expressing republican views. Extraordinary – and shocking – that this needs saying.”
Met Police Deputy Assistant Commissioner Stuart Cundy said: “The public absolutely have a right of protest and we have been making this clear to all officers involved in the extraordinary policing operation currently in place and we will continue do so.”
On the issue of policing protests, the Prime Minister’s official spokesman said: “This is a period of national mourning and indeed grief for the vast majority of the UK and I think that’s what you are seeing borne out.
“I’m not going to be drawn on operational policing decisions. The police have a challenging job to do… but the right to protest does remain a fundamental principle.”
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