Some London Underground carriages remained crowded on Monday despite a further fall in passenger numbers.
Passengers complained about the lack of space as they travelled to work, leading to them being unable to follow Government guidance to keep two metres away from others.
Transport for London (TfL) has called for its services to only be used for “essential journeys by vital workers in the NHS and other critical services”.
It said passenger numbers on Monday morning were down 94% compared with the same day last year.
Demand on the previous Monday was down 85% year-on-year.
But a Central line passenger, who did not want to be named, said there were “plenty of commuters” on the platform at Leytonstone station, east London on Monday morning.
She told the PA news agency: “People observed social distancing whilst on the platform but as soon as the train arrived everyone moved towards the doors.
“Perhaps there should be an announcement that commuters should take their time in getting on and off.”
Another woman who did not want to be named said she is concerned about her partner catching coronavirus on the Tube, particularly as they are both NHS nurses.
She commented: “My partner is an NHS registered nurse going to Westminster from Newbury Park Tube.
“It is so difficult to get a seat, even at 6am.
“I’m worried that she will catch the virus herself and get ill but also pass it on to her colleagues or me.
“I am also an intensive care and high dependency unit registered nurse.
“This will take us away from critically ill patients during this very trying time.
“We are already at reduced numbers of registered nurses in intensive care and high dependency units, even before Covid-19. Now the situation is worse.”
Train drivers’ union Aslef posted a video showing a crowded platform with passengers stood shoulder-to-shoulder waiting to board a service.
It also posted a message which read: “Shocking scenes again on London Underground this morning. Workers being forced to take unnecessary journeys by unscrupulous employers.
“Government must take action to close non-essential workplaces so our members can continue to provide safe services for key workers.”
Tube services have been reduced by around 50%.
Last week, Prime Minister Boris Johnson told MPs it should be possible to “run a better Tube system”.
But Mayor of London Sadiq Khan insisted “we cannot run more services” as a third of staff are ill or self-isolating.