RADICAL schemes for two off-shore airports in Kent are to be given fresh consideration by ministers.

The Department of Transport has confirmed that it has invited the backers of terminals on the Hoo peninsula and the Isle of Sheppey to submit more details of their projects.

Ministers are understood to have asked those behind the schemes for a fuller analysis of the costs of road and rail improvements, potential passenger numbers and other infrastructure costs.

The move comes two months after the end of the official consultation period on airport expansion, including the controversial Cliffe plan.

One of the consortia is Marinair, which has suggested a £31.5billion Thames Estuary Airport, capable of carrying 23 million passengers a year.

A second option is for an Isle of Sheppey airport, built partly on shore and partly on a raised platform beside the Hoo Peninsula.

Both options have previously been regarded by industry insiders as extremely unlikely to happen.

A spokesman for the Department of Transport said: “We’re helping them to develop their proposals so we can compare them on a consistent basis with the options we’ve put forward.”

The spokesman added that it was up to the consortia involved to come forward with the information. “Alistair Darling [transport minister] does not want to rule anything in or out.”

Labour MP Derek Wyatt, who represents Sittingbourne and Sheppey, said campaigners opposed to the schemes should not be alarmed.

“My view is that the Department of Transport has taken legal advice after the legal challenge Kent and Essex County Councils made over Gatwick being excluded from the original consultation and does not want to risk further legal challenges,” he said.

Mr Darling is expected to announce at the end of the year where extra aviation capacity will be provided. The Cliffe airport plan is among the options but is said not to be among those favoured by ministers.