Among those named is Trump's personal lawyer Rudy Giuliani.

In addition, lawyers Jenna Ellis, Sidney Powell and political strategist Boris Epshteyn have been called to testify before the committee.

Want answers to speeches

What the committee wants answers to are questions linked to unfounded allegations of widespread electoral fraud and that the 2020 presidential election has been "stolen".

The people called to testify have stubbornly claimed that the election was stolen and that it was Republican Trump and not the current president, Democrat Joe Biden, who won the 2020 presidential election.

Trump stands his ground

Trump also continues to claim election theft, without proof of the accusation.

"The four people we have called today have put forward theories of electoral fraud and they have worked to overthrow the election result," said committee chairman Bennie Thompson, a Democrat, in a statement.

The Committee would also like to ask Giuliani for documents that would support his allegations of electoral fraud, as well as answers to questions concerning his attempt to persuade members of Congress to take steps to have the election results rejected.