Workers on London Underground's Waterloo and City line are to stage a two-day strike in a regrading row.

Members of the Rail, Maritime and Transport union based in the control room will walk out at 9pm on September 28.

RMT general secretary Mick Cash said: "LU management must be clear by now on our members' legitimate and reasonable demand for regrading.

"The union has re-iterated that we will not accept an offer which is based on a change in staff duties or which would cause a detriment to other members."

Peter McNaught, London Underground's operations director for the Waterloo & City line, said: "We are working on our resilience plan to minimise the impact on the line should this unnecessary strike action go ahead.

"We've been in extensive discussions with the RMT over this issue during the past year and we've presented various options to bring this dispute to an end.

"These have included exploring development opportunities to help progress the careers of the staff concerned as well as allocating additional responsibilities that would justify a salary increase.

"Unfortunately all of these options have been rejected outright by the RMT who appear determined to demand more money for no additional work or responsibility.

"We remain committed to discussions with the RMT representatives and I urge them to consider the options we've proposed rather than threaten industrial action."