Theresa May called the building of a Holocaust Memorial in Westminster "a sacred, national mission,” as she reiterated her support for the project that has suffered setbacks.

The Prime Minister issued a new message backing the project in Victoria Tower Gardens ahead of a Holocaust remembrance event in London on Tuesday.

In a video to be played at the event, Mrs May says: “By putting our National Holocaust Memorial and Education Centre next to our Parliament, we make a solemn and eternal promise that Britain will never forget what happened in the Holocaust.

“Seeing this through is a sacred, national mission. In the face of despicable Holocaust denial, this memorial will stand to preserve the truth forever.

“And this education centre will ensure that every generation understands the responsibility that we all share – to fight against hatred and prejudice in all its forms, wherever it is found.”

Mrs May was joined by the all the living former prime ministers - David Cameron, Gordon Brown, Tony Blair and Sir John Major.

A planning application for the project, which was first proposed in 2016, has been lodged with Westminster City Council but architects have said they will submit a smaller design, after opposition from heritage and environment groups about the design's impact on Victoria Gardens.

Royal Parks, which manages the space, said it would have a "significant and harmful impact" on the park, which is next to the Palace of Westminster.

In his message, Mr Blair says: “Antisemitism and hate did not end in 1945. Unfortunately today some of this poison is back from the political fringe to parts of the political mainstream.

“So, it’s absolutely right that this new national memorial is situated right next to Parliament. So we can show what happens when racism and prejudice go unchecked.”

Mr Blair's successor as Labour leader, Jeremy Corbyn, said in his message he would “strongly support permanent commemoration, including a national memorial, alongside extra investment in educational programmes.”