Officials at the UK prime minister's office in 10 Downing Street have refused to comment on reports that

In the US President Bush has two VC-25As - converted Boeing 747s known as Air Force One when he is onboard, while Russian President Putin uses a modified Ilyushin Il-96. But Blair has relied on RAF Vickers VC10 transports, which are coming to the end of their useful life, and chartering British Airways aircraft.

It is understood that Blair's advisers are looking at security considerations and costs because the prime minister has been racking up so many air miles on round-the-world diplomacy that a vip aircraft may be cost-effective.

However, MPs of the ruling Labour party pointed out that plans for a 'Blair Force One' might be short-lived with expectations that chancellor Gordon Brown will take over as prime minister within a year or 18 months.