But London Underground said staff would only be moved around, not cut.

The Rail, Maritime and Transport (RMT) union said front-line station staff is to be cut "in droves". On Thursday it will finish balloting 4,000 station workers for strike action.

"There have been widespread calls for more uniformed staff after the recent bomb attacks, but LUL has responded by cutting visible station staff in every singe zone one station," RMT general secretary Bob Crow said.

Basic grade station assistants at the three sites attacked on July 7, Kings Cross, Liverpool Street and Edgware Road, would be cut by 75%, 70% and 30%, he claimed. Waterloo would lose 60%, and Green Park, Baker Street and London Bridge about half.

However, London mayor Ken Livingstone strongly denied the allegations. "There is no reduction in staffing," he said at his weekly press conference.

Workers would just be moved out of ticket offices onto platforms to be more visible, he added.

Some staff would also be moved from central London to the outer zones to "provide reassurance".

LUL said the restructuring is part of a deal agreed with the RMT a year ago to reduce the work week from 37.5 hours to 35 hours. The union then hailed the deal as "groundbreaking" and its members backed it 30-1 in a vote.

Because of the success of the Oyster smartcard, used by 2.9 million passengers, LUL sells one million less paper tickets a week. "This means passengers are queuing for tickets less," an LUL spokesman said.

Ticket office staff would now be used elsewhere to implement the shorter work week, he added. "There are no staff cuts across the Tube network as a whole."

Staff at any individual station would also not be cut "by anything like the numbers the RMT claim", he said. "Indeed, at some stations such as Paddington, Camden Town and London Bridge, we are actually increasing the number of staff.

"We very much hope that this dispute can be resolved without the need for strike action and are continuing to talk to the RMT."

DLR strike threat averted
Meanwhile the threat of another RMT strike, by 250 Dockland's Light Railway (DLR) workers, has receded.

The company made a "massively improved" pay offer, which includes a 5.25% raise in two stages, travel concessions and a New Year's bonus of £100, the union said.

It has started to ballot members for strike action after the DLR reduced a previous pay offer from 3.4% to 3.25%.

Although the ballot will still conclude tomorrow, union bosses will recommend that members accept the new deal.