Businesses based at Dover docks - and all other ports in Kent - could be hit with multi-million pound back-dated rates bills under a radical change introduced by the Government.

Companies operating out of Hull - including Dover-based P&O Ferries - have already been sent huge bills for rates dating back to 2005 and it is expected the same will happen at other ports across the country during the coming weeks.

Business people fear it could result in bankruptcies and redundancies.

The change applies to the way that business rates are charged to companies that use ports and to compound the agony the process is being backdated.

At Hull the new system has just been applied to 39 businesses, large and small. P&O Ferries faces a backdated bill of £5million to 2005 plus £2.4million for the current year.

Other companies face bills for £3million and and £1.3million.

The combined annual rates bill under the old system at Hull was just over £3million before 2005.

Under the new system the rates collectable in 2008, with the backdating, tops £20million.

Valuation officers are now applying the new process to companies that operate from other ports across England and Wales and companies based and businesses based at Dover are bracing themselves.

"Rates have already been paid under the old system, so backdating shouldn't arise," said a spokesman for P&O Ferries.

"Looking ahead, the new bills are so detached from commercial reality that there can be no doubt they'll drive some smaller companies to the wall.

"Unless the Government wants to decimate the shipping and logistics sector, it should call a halt and reconsider the whole sorry mess."

Richard Thornby, estates manager at Peel Ports, which runs Chatham and Sheerness Docks, said: "The valuation officer has been round and we expect to know sooner rather than later what the effects of all this will be.

"It is of major concern to us and our tenants. Previously the rates were based on the cumulative turnover of the ports but now they are based on the individual buildings and tenants within the port.

"We have known about this for about a year but are still awaiting what effect it will have.

"The port of Hull was the first to be trialled by the Government but it will now affect all 54 commercial ports in the UK."