MYSTERY surrounds the theft of laptop computers belonging to the former North-East police chief investigating the death of Princess Diana.

Offices in the Gosforth area of Newcastle used by Lord Stevens of Kirkwhelpington, who headed the Northumbria force for five years before becoming Commissioner of the Metropolitan Police, have been broken into twice within a week.

The first raid, according to police, happened on the weekend of January 28 and 29, when two computers and some cash were stolen. The second happened this weekend, though nothing was taken.

Lord Stevens' former force said last night that there was nothing to suggest a link between the raids and his role heading Operation Paget, the probe into Diana's death in a car crash in a Paris tunnel, in August 1997.

The French authorities blamed the tragedy, which also killed Diana's boyfriend, Dodi Fayed - son of Harrods owner Mohammed Al Fayed - on their chauffeur, Henri Paul, who was said to have been drunk.

But various conspiracy theories have sprung up since, including suggestions that she was killed by, or on behalf of, the British intelligence services in an engineered accident.

Lord Stevens, who is believed to use the Tyneside offices for his business interests, has said the inquiry is "more complex than any of us thought", and it is expected by some observers that it could uncover some startling information.

A source for Lord Stevens, who has also investigated allegations of collusion between British forces and Loyalist terrorists in Northern Ireland, said the thefts would not compromise the inquiry.

It is believed the inquiry, made up of a team of 12 Met detectives, has offices in the capital.

A Northumbria Police spokeswoman said: "Detectives in Northumbria are investigating two break-ins at the Dobson office block at the Regent Centre, Gosforth, in Newcastle.

"While the laptops were stolen from a suite of offices sometimes used by Lord Stevens, there is nothing to suggest that this burglary is in any way linked with his work as the Commissioner of the Metropolitan Police or any investigations which he has been involved in, either now or in the past.

"It is not unusual in Newcastle area command for commercial premises to be targeted for laptop thefts."