There may be “significant disruption” on the London Underground during the Christmas period as rail workers decide on whether to engage in strike action.

One thousand Tube cleaners from the Rail, Maritime and Transport Workers (RMT) union today began voting on whether to take industrial action in a bid for better pay and amenities.

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The cleaners are demanding an increase to their £19,029 annual salary and the same access to pensions and sick pay that other London Underground staff have.

They are also fighting to gain free access to free Transport for London (TfL) travel, which all other Tube workers get.

RMT general secretary Mick Cash said: “It is scandalous that the people who do some of the hardest and dirtiest work on London’s transport network are treated differently to other London Underground staff.”

The ballot on whether to strike ends next Tuesday and may lead to industrial action as soon as 2 December.

There are around 2,000 cleaners employed to work at Tube stations across the capital, with half of them signed up as members of the RMT.

Cash said the strikes could back the system up and cause delays throughout the Christmas period.

“The cleaners on the London Underground are key to keeping services moving – if a train is soiled by a member of the public it cannot move on until it has been cleaned and that happens more often than you would think,” he said.

“Any strike would cause significant disruption.”

The cleaners are all hired by multinational outsourcing company ABM.

A spokesperson for the US-based company said it offered pay and benefits that “compare favourably” to other UK cleaning companies.

“We are disappointed that RMT is balloting its members for strike action,” they said.

“A strike threatens unnecessary disruption and delay for the millions of customers that rely on the Tube every day.”

If the cleaners go on strike they will join fellow RMT members from South Western Railway (SWR), who are walking off the job for 27 days in December.

Read more: Business groups warn RMT rail strikes will hurt Christmas trade

The SWR strikes will start on 2 December and last until the New Year, with only brief breaks around the 12 December election and Christmas day.

CBI chief UK policy director Matthew Fell labelled the strike action as “deeply unfair to businesses, commuters and families in the busy run up to Christmas”.