BORIS JOHNSON must reverse ticket office closures to stop nightmare travel chaos at some of Britain’s busiest stations, rail unions blasted yesterday.

Bottlenecks have built up regularly at London’s Victoria, Euston, King’s Cross and Liverpool Street mainline termini and station staff have been diverted to deal with queues at ticket machines.

The London mayor announced the closure of every ticket office on the London Underground in 2013 — despite pledging to keep them open when he stood for re-election the previous year.