Commuters face an increased threat of travel chaos because of strikes by rail workers later this month, it was warned today.
The Rail Maritime and Transport union said its members on Docklands Light Railway in London will walk out for three days from 4am on June 23 in a row over pay.
The strike by staff employed by Serco will coincide with the first of two 48-hour stoppages by London Underground maintenance workers employed by Tube Lines.
RMT general secretary Bob Crow said: "Our members on the Docklands Light Railway have shown once again that they will not be bullied by management into taking on more work and more responsibility without being properly compensated by the company.
"RMT has made every effort to reach a negotiated settlement on this issue but all of our proposals have been thrown back in our face. That is no way to run a key element of London's transport system.
"We remain available for further talks and hope that in light of the massive mandate for action that has been delivered by our members that Serco will now get back round the table and take our proposals for compensating our members for this major change to the DLR seriously."
The Tube Lines workers are due to stage two 48-hour strikes from June 23 and July 14 in a separate row over pay, jobs and conditions.