TWENTY thousand Tube workers are to ballot on strike action over the prospect of “absolute chaos” if hastily drawn-up plans to run all-night services are implemented.

Four trade unions have united in a campaign of resistance to the plans, which rail union RMT says will “rip up the safety rule book” and hit crucial engineering and maintenance work.

The other three unions are Aslef, representing train drivers, TSSA, which organises white-collar staff, and general union Unite.