US President Donald Trump has said the “existing structure” of the White House East Wing must be torn down in order to construct a new $250m (£186m) ballroom.

Crews began demolishing parts of the structure on Monday, and two administration officials earlier told the BBC’s US partner CBS that it will be completely torn down by the weekend.

It marks a significant expansion of the construction project announced over the summer. Trump previously said his ballroom addition would not “interfere with the current building”.

He rejected accusations he had not been transparent over the extent of the works, telling reporters on Wednesday: “I think we’ve been more transparent than anyone’s ever been.”

The White House has served as the historic home of the US president for two centuries. The East Wing was constructed in 1902 and was last modified in 1942.

It is a section of the White House that holds offices for the first lady and other staff, as well as meetings and special events.

Trump said the building had gone through several changes over the years and was “very, very much changed from what it was originally”.

He added that was “never thought of as being much” and that the changes have been wanted “for at least 150 years”.

The construction was being fully funded by Trump and “some friends of mine – donors”. The military is also involved, he added.

The US president announced construction had begun in a social media post on Monday, saying “ground has been broken” on the “much-needed” ballroom space.

He said that the East Wing was “completely separate” from the White House, although it is attached to the main structure.

The Trump administration officials told CBS it was always the case that the East Wing would have to be modernised to enhance security and technology, but that during the planning process, it became apparent that the best option would be to demolish the entirety of the East Wing.

His comments came after the National Trust for Historic Preservation, a Washington non-profit organisation that protects historic US sites, wrote a letter to White House officials saying it was “deeply concerned” by the project.

The trust asked Trump to pause demolition work, arguing that the White House was a national historic landmark and that officials needed to hold a public review process of the plan for the ballroom.

Some Democrats have been critical of the renovation, including Hilary Clinton, who ran against Trump for the US presidency in 2016.

In a post on X, she wrote that the White House was not Trump’s house, and “he’s destroying it”.