Transport Secretary Lord Adonis has scrapped his predecessor Geoff Hoon's plans to take over the running of Heathrow if London's premier airport got into got into financial difficulty.

However new plans announced today have sparked a debate, with airports regulator the Civil Aviation Authority (CAA) insisting it will not allow the likes of Heathrow to raise prices to shore up its finances.

At the height of the financial crisis, Hoon put forward plans to take Heathrow, Gatwick and Stansted into “special administration”.

But announcing a U-turn today, Adonis put the onus on the CAA, saying its duty to protect passengers has been extended to ensure airport owners — in this case BAA — can finance their activities.

The CAA immediately quelled suggestions it will automatically help out cash-strapped airport operators at the cost of the passenger.

In a statement, the CAA said Adonis had confirmed the regulator would not have “to adjust regulation of price, service and investment to take account of an airport operator's particular financial arrangements”.

The U-turn was welcomed by BAA as “removing key uncertainties”. Bondholders carrying £10 billion of BAA debt feared they might be wiped out under Hoon's plan.