London Mayor Sir Sadiq Khan echoed the call and described the industrial action as “bad news for London”.
“TfL have made clear they can’t afford its workers working fewer hours for more pay, but they are willing to talk to the RMT and other unions whenever there is a dispute and to try and resolve things amicably,” he said.
The transport body has offered RMT members a pay increase of 3.4% but argue that reducing their work week to 32 hours would cost hundreds of millions of pounds.
Jared Wood, an organiser with the RMT, said: “They’re throwing in everything they can imagine to come up with a figure of hundreds of millions – it would not be near hundreds of millions to make real progress.
“At the end of this week we hope to be in meaningful discussions where the company comes up with a way of resolving this.”