LONDON Mayor Sadiq Khan must intervene in an increasingly bitter dispute over pay and pensions on London’s flagship Elizabeth line, transport union TSSA demanded today.

In a letter, interim general secretary Frank Ward warned that today’s “crippling strike,” which brought the central section of the new line to a standstill, will only continue if bosses refuse to negotiate.

Staff, also represented by unions RMT and Prospect, warn that employer Rail for London Infrastructure Limited — a subsidiary of Transport for London (TfL) — are forcing through pensions changes and paying workers up to £30,000 less than colleagues with equivalent roles elsewhere.