The paper announced it had acquired "exclusive world rights" to the story by fighting off bids from more than 400 media organisations worldwide.

Last Friday, Mr Burrell was found not guilty of three charges of stealing from Diana's estate, after it was revealed he had told the Queen he was keeping some of the princess's possessions.

Mirror editor Piers Morgan told the BBC members of the Royal Family and the Spencer family could be embarrassed by the revelations.

Piers Morgan said it was "an utterly compelling story".

Earlier on Monday, Mr Burrell, 44, spoke for the first time on LBC Radio and thanked the British public for their support since his trial collapsed.

"I want to come out and tell you what's happened to me. I do have a great story to tell," he said.

The Mirror will start publishing Mr Burrell's revelations on Wednesday.

Mr Morgan told BBC News on Monday his paper had agreed to pay "about �300,000" for the story.

There will be people out there who have knifed him firmly in the back who I suspect will be having a few sleepless nights

Piers Morgan Mirror editor

He said: "He will be incredibly frank, I think it will be pretty searing stuff.

"He will protect the memory of Princess Diana and will honour his pledge to always protect the Queen.

"But I think there will be many others in the Royal Family and those close to the Royal Family who will be quaking in their boots tonight."

The Mirror editor denied the story would distress princes William and Harry.

Queen's role

Mr Burrell said he had been offered more than �1m for his story, "but I am not interested in just making the most amount of money that I can".

"I believe that the Daily Mirror will let me tell the true story as it is."

Media lawyer Mark Stephens told BBC News it was a story worth "many millions" and said: "Piers Morgan and the Mirror have really got a scoop and a steal."

He added he thought the story would probably provide the former butler's perspective on facts already in the public domain, and not betray any confidences.

Mr Burrell told the Queen he was looking after Diana's things

Mr Burrell earlier told LBC Radio: "It has not been easy for me and my family but the great British public has been a tremendous support.

"We have received sacks of mail from all round the country and it is very moving and touching."

Mr Burrell said he would be doing his best to read all the letters and to answer as many as possible.

He added: "I need to know what people are thinking. It has always been my policy to keep in touch with the factory floor."

Meanwhile, Prime Minister Tony Blair defended the Queen's role in bringing to light evidence that acquitted Mr Burrell, saying she had acted "entirely properly".

Labour MPs have demanded to know why the Queen delayed intervening and have demanded she pay the costs of the �1.5m trial.