King Charles thanks mourners for 'support and comfort' before Queen's funeral

Family is 'moved beyond measure' by those who turned out to pay their respects

King Charles III and Queen Consort Camilla inspect floral tributes left for his late mother Queen Elizabeth II outside Hillsborough Castle in Northern Ireland. Getty

A picture of Queen Elizabeth is among flowers left by mourners outside Buckingham Palace in London. AFP

Members of the public leave flowers and tributes at The Long Walk gates in front of Windsor Castle in Windsor, England. Getty

Members of the public look at flowers and tributes left in Green Park in London. AFP

Flowers and tributes placed by mourners at the Cambridge gate outside Windsor Castle, west of London. AFP

A child lays flowers in remembrance of Queen Elizabeth outside the Palace of Holyroodhouse in Edinburgh. AP

King Charles III has thanked all the people who have provided “support and comfort” following the death of his mother, Queen Elizabeth II.

He and Queen Consort Camilla were "deeply touched" by the many messages they had received from around the world, the new king said on the eve of his mother’s state funeral.

Queen Elizabeth’s funeral on Monday is a huge security operation, with organisers having to ensure that international leaders attending it are safe amid the national mourning.

Tens of thousands of people joined the kilometres-long queue in London on Sunday to pay their last respects to the queen lying in state in Westminster Hall.

"Over the last 10 days, my wife and I have been so deeply touched by the many messages of condolence and support we have received from this country and across the world,” Charles said in a written message issued by Buckingham Palace.

"In London, Edinburgh, Hillsborough and Cardiff, we were moved beyond measure by everyone who took the trouble to come and pay their respects to the lifelong service of my dear mother, the late queen.

"As we all prepare to say our last farewell, I wanted simply to take this opportunity to say thank you to all those countless people who have been such a support and comfort to my family and myself in this time of grief."

Westminster Abbey will be the venue for the spectacular state funeral for the queen, who died aged 96 on September 8.

About 2,000 people, including royalty, presidents and prime ministers, will be in the gothic church for a day of pageantry, military processions and solemnity in honour of the late monarch.

Mourners outside Buckingham Palace. AFP

About 26,000 people an hour passed through security barriers at Westminster Hall on Sunday in a long queue to see the queen's coffin. Many started the journey in Bermondsey, east London.

At 8pm on Sunday, the country observed a one-minute silence to remember the queen.

Mayor of London, Sadiq Khan, said the funeral presented an “unprecedented” security challenge.

One of the UK's biggest transport operations is also being set up, with Transport for London preparing for about one million visitors on Monday.

There are fears the transport network will be overwhelmed if too many people visiting the capital travel home as soon as the funeral procession leaves Westminster.

Charles and Camilla returned to Buckingham Palace on Sunday to host world leaders and official overseas guests at a state event.