In a joint statement TSSA, ASLEF and RMT have warned of the "increased risks" of reducing social distancing on public transport at the current time.
ASLEF general secretary Mick Whelan, RMT Senior Assistant General Secretary Mick Lynch and TSSA General Secretary Manuel Cortes said:
"The government’s own advisors have said that reducing social distancing to one meter will significantly increase the chance of infection by up to 30 times, whilst the chances of Covid-19 spreading are increased in confined spaces such as train carriages and stations.
"It is also the case that the threat of infection from the virus has not changed significantly whilst at the same time we are already seeing increases in rail and tube use which may further rise after 4th July.
"Policing two metre social distancing on public transport is already challenging and reducing it to one metre will make it almost impossible. In these circumstances diluting social distancing on public transport could increase risks so we cannot support a change to the social distancing measurement at the current time.
"We wish to see a safe and sustainable increase in public transport as soon as possible but not at the expense of worker and passenger safety.”