Britain's best-known defence lawyer has claimed that the death of Princess Diana was brought about by a failed attempt to frighten her into leaving lover Dodi Fayed.

Michael Mansfield QC, who represented Dodi's father, Mohamed Al Fayed, at the six-month inquest in 2008 into the couple's deaths, said he was sure Diana's killers had no intention of ending her life in a Paris underpass in August 1997.

But he claimed an operation to torpedo her relationship with Dodi and silence her planned criticism of the Government over land mine sales abroad, backfired spectacularly.

"I don't believe anyone wanted to see her dead. I think there was a plan to sabotage the relationship and alter her life, to try to stop her activities. But this plan went very badly and ended with her death," the Daily Express quoted Mansfield as saying in an interview with the Barcelona-based newspaper El Periodico.

The radical QC, whose long list of famous cases has included the Jean Charles de Menezes inquest, has previously claimed Diana's death was no accident.

He outlined his views in memoirs published last year on his colourful 40-year career. But his latest comments offer further insight into his feelings about the case.

Mansfield said British authorities opposed several aspects of Diana's private and public life.

"I believe the relationship between Diana and Dodi displeased the authorities. In spite of all the work Mohamed Al Fayed did for children and hospitals, he was persona non grata in Britain," he said.

Adding: "Diana had given interviews attacking the Royal Family, but what most annoyed the authorities was that Diana became very actively involved in the campaign against land mines."

An inquest jury concluded that the grossly negligent driving of chauffeur Henri Paul and pursuing vehicles had unlawfully killed Diana. (ANI)