Control room staff of the London Underground (LU) operated Waterloo & City line are planning a 48-hour Tube strike next week.

The Waterloo & City line, which is used by more than 35,000 commuters every day, will be shutdown from next Monday as the workers are seeking solutions to key re-grading issues.

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

"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.

"Although LU has declined our request for arbitration at ACAS, they are aware that as always we remain available for talks to resolve the dispute."

"We are working on our resilience plan to minimise the impact on the line should this unnecessary strike action go ahead."

The control staff workers are members of the Rail, Maritime and Transport Workers (RMT), which is one of four unions in negotiations with LU over the Night Tube.

The other union members include Associated Society of Locomotive Engineers and Firemen (ASLEF), Unite and the Transport Salaried Staffs Association (TSSA), which are reportedly not involved in the Waterloo & City line pay dispute.

RMT noted that 100% of its members on the lines voted in favour of the strike.

The Waterloo & City service control staff will not book any shifts between 28 September 9pm and 30 September 11pm.

According to Transport for London (TfL), train drivers will not be involved in the strike and there are only eight control room staff working on the line, six of whom are RMT members.

The LU and union leaders previously contested how many people actually voted for the proposed strike.

LU Tube said that out of the six control staff eligible to vote only three voted for the walkout while the RMT claimed that there were 24 voters and all voted for a strike.

London Assembly Tory spokesman for transport Richard Tracey told the Evening Standard: "It is disgraceful that such a tiny number of people should be able to cause huge disruption on a major route into the City.

"This is exactly the sort of industrial action we have been complaining about."

LU Waterloo & City line operations director Peter McNaught 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."