Economists have warned that strikes on Tuesday, Thursday and Saturday could cut between 0.3% and 0.4% of gross domestic product by June, with one in 20 people unable to go to work.
Other public sector unions are threatening to follow the railway workers and take action, with teachers preparing to vote for a strike if they do not receive a wage settlement close to inflation.
The National Education Union said that unless it receives a salary offer closer to inflation on Wednesday, it will inform Nadim Zahawi, the secretary of education, who plans to vote 450,000 members.
NHS workers could also leave if the pay rise to be announced this week does not keep pace with inflation, which is expected to reach 11 per cent this year.
Christina McAnea, the head of Unison, the largest union in the country with NHS staff among its members, warned the government that it was faced with a choice: to make a “reasonable wage award … or risk a possible dispute “.
It is understood that the national executive of the RMT will begin planning the next round of rail strikes over the weekend.
A union source said: “We have a six-month strike mandate. The National Executive Committee will decide what to do next. They will only meet after this week and then have to warn employers two weeks in advance.”
The RMT can call strikes with only fifteen days notice until the end of November, six months after the results of the voting were returned at the end of May. More industrial action after that would require a new vote.
The two sides in the rail dispute remained on the sidelines on Sunday, with new talks scheduled for Monday. The Telegraph has learned that Network Rail offered an initial two per cent increase and a demand for job cuts, while RMT Secretary-General Mick Lynch revealed for the first time that he was demanding wage increases of at least seven percent.
When asked if passengers should expect a “long fight,” Mr. Lynch told the newspaper and, “Maybe it should be like this, I hope not, but there doesn’t seem to be much evidence at this point that it will go any other way.”
Network Rail said the company was now being investigated for “a battle of attrition” that echoed the mid-eighties miners’ strike.
A Network Rail source said: “These strikes are very unlikely to be timely. The RMT will meet after the strikes and decide what comes next and we assume there will be more interruptions and more strike days. the dispute over a battle of attrition.
“We are looking to pay extra money to the RMT signals to break the strike. Nothing has been decided, but there have been discussions about doing so.”