London Underground workers are threatening to go on strike following a spate of rows over pay, sackings and staff transfers.

The Rail, Maritime and Transport Union (RMT) is involved in seven rows with Tube contractors and has claimed a "sharp increase" in complaints about bullying of workers.

The disputes involve more than 2,000 workers, including cleaners, maintenance and station staff and the RMT warned of possible co-ordinated action.

The biggest dispute involves 1,000 workers employed by maintenance firm Tube Lines who are being balloted for industrial action over pay, with the result due later this week.

Hundreds of cleaners and staff who put up advertising posters at Tube stations have already taken strike action in disputes over pay which remain unresolved.

Union members have also been on strike in support of a sacked colleague and over staff transfers while ballots are currently being held over another sacking and in a separate row over industrial relations.

Bob Crow, general secretary of the RMT, said: "There has been a spate of clearly unfair sackings and a sharp increase in complaints our reps are receiving about bullying and harassment.

"It seems that local managements have been slipped off the leash and a blind eye is being turned to their excesses.

"There are people being treated appallingly and each of these issues needs to be sorted but if they are not we will look to co-ordinate strike action to make sure they are."

© Independent Television News Limited 2009. All rights reserved.