LONDON: Prince William has called an investigation into claims that his mother Princess Diana was tricked into agreeing her bombshell 1995 BBC interview a "step in the right direction".

The late princess' brother, Charles Spencer, has alleged the flagship "Panorama" programme reporter who conducted the interview, Martin Bashir, showed him faked documents to persuade his sister to take part.

The BBC announced Wednesday the immediate start of an investigation, a move welcomed by the prince.

"The independent investigation is a step in the right direction," William, 38, said late on Wednesday.

"It should help establish the truth behind the actions that led to the Panorama interview and subsequent decisions taken by those in the BBC at the time."

Diana detailed her collapsing marriage to the heir to the throne in the November 1995 interview, which was watched by a record 22.8 million people.