Seriously ill people are being put at grave risk in overcrowded emergency departments where paramedics are still regularly stuck in long queues, doctors warn.

Nearly two years after the Labor party vowed to fix Victoria's ambulance service, leaked data indicates there has been no improvement in ambulance "ramping" and that this month hundreds of patients waited longer than an hour to get into an emergency department while under the care of paramedics.

The man is in a critical condition. Credit:Paul Rovere

The queues are tying up paramedics when they should be free to respond to urgent cases. Doctors say the problem persists because hospitals are too full.

The leaked Ambulance Victoria data shows that during the first two weeks of September, there were 10 days when one in 10 patients arriving at Melbourne hospitals via ambulance were stuck in a queue for more than an hour because emergency department staff did not have enough resources to accept them.