The Blairs' first-class freebie... or why British Airways is Tony and Cherie's favourite airline

Tony Blair enjoyed free airline upgrades worth thousands of pounds during his controversial holiday to the Miami mansion owned by Robin Gibb, the former Bee Gee, The Independent on Sunday can reveal.

The Prime Minister yesterday faced fresh accusations of "freeloading" after it emerged that he and Cherie Blair were upgraded by British Airways to first class on two transatlantic flights during the Christmas break.

MPs said Mr Blair had become a national embarrassment for repeatedly failing to pay his own way. Mr Blair has taken "free" holidays worth more than £775,000 with wealthy hosts since taking office. They include four holidays at a Barbados villa owned by Sir Cliff Richard.

Yesterday Mr Blair was accused of using his position to "blag" first class tickets to Miami, where he was staying at a luxurious house owned by Mr Gibb.

The upgrades are worth thousands of pounds. The cost of a first class return ticket to Miami is around £7,000, compared with an economy fare sold for as little as £350. A business class ticket costs around £3,500, depending on when the ticket is booked.

"Tony Blair has become the ultimate freeloader," said Norman Baker, Liberal Democrat MP for Lewes. "He seems to have no shame. It's completely inappropriate for the Prime Minister to behave in this way. Normal people are not upgraded in this way. He is clearly using his position to get yet another freebie. Why doesn't he just pay his own way like everybody else?"

The Prime Minister revealed the upgrades in the latest edition of The Register of Members' Interests, where he said that he paid for the flights to Miami and London himself.

But British Airways yesterday confirmed that the Prime Minister has yet to pay for the upgrade to business class from economy that he requested on checking in at Heathrow, and will be invoiced.

After requesting that he, but not Mrs Blair, receive an upgrade from economy to business class, both he and Mrs Blair were offered complimentary first class tickets. On the return flight from Miami Mr Blair was also upgraded from business to first class.

"I met the cost of all flights. My wife and I were upgraded by British Airways on the flight to Miami and I was upgraded by British Airways on my return flight from Miami," he said in The Register of Members' Interests.

The airline confirmed the Prime Minister was to be invoiced for the cost of the difference between an economy and a business fare.

"Anyone can pitch up at check- in with a ticket for a lower cabin and ask to pay to be upgraded," said a BA spokesman. "I think that's what happened in his instance. The Prime Minister bought a business class return to Miami shortly before departure, for which he is to be invoiced. As we do with our passengers from time to time for commercial reasons, we offered Mr and Mrs Blair an upgrade. At our discretion we upgraded the Prime Minister and Cherie into first."

Mrs Blair was joined by Mr Gibb and his wife, Dwina, at their mansion before a New Year's Eve party. The house is in a prime location with spectacular views of the Miami sunset. Mr Blair is said to have taken his Fender Stratocaster guitar on the holiday, prompting speculation he might have a jam session with the pop star.

Mrs Blair is friends with the pop star and with Mrs Gibb, a Druid and artist. Flanked by outriders in 4x4s and police motorcycle riders, the Blairs were spotted cruising around Miami with a posse of Scotland Yard bodyguards.

Mr Blair has enjoyed holidays at the private homes of a string of pop stars, businessmen and politicians since coming to power. He was a guest at the home of Silvio Berlusconi, the former Italian Prime Minister, who owns a mansion in Sardinia.

Alain Dominique Perrin, a former executive of Richemont, the company behind the Cartier brand which owns a stake in British American Tobacco, allowed the Blairs to stay at his chateau.

Mr Blair has also not been shy about accepting free travel since becoming Prime Minister. In December 2005 he accepted flights from the King of Jordan after official talks.

Additional research by Puja Awasthi

... and he's not in the clear over the Bee Gee's villa either

Tony Blair is to face fresh questions this week over exactly how much he paid to rent the £5m Florida home of Robin Gibb (pictured below), the former Bee Gee.

Mr Blair, who spent his winter holiday in Miami with his family, claims he rented the villa, coming to "a private commercial agreement made through Mr Gibb's manager".

But MPs have questioned whether Mr Blair paid market rates.

Florida estate agents say that a villa as luxurious as Mr Gibb's, which has 10 bedrooms, could cost as much as £40,000 a week to rent. MPs believe he only gave a token amount.

Downing Street officials have suggested that the money has been paid to charity.

Yesterday the Tory MP Chris Grayling called on the Prime Minister to set the record straight.

"This whole trip has been mired in confusion and controversy. The trouble is that when the Prime Minister makes a non-specific declaration people think there's something to it," he said. "I think it would be helpful if No 10 for once gave us a full, frank and detailed explanation."