Doctors who oppose the Morrison government's push to repeal controversial medical transfer laws say their analysis of previously hidden medical records shows at least three quarters of refugees and asylum seekers in Papua New Guinea and Nauru have a serious physical health condition.

In a submission to a parliamentary inquiry, the doctors have used an audit of six years' worth of refugees' medical files - obtained under the so-called 'medevac' laws, which the government is pushing to overturn - to claim the average offshore patient seeking medical transfer to Australia has 4.6 serious physical ailments.

Asylum seekers in the now-closed Oscar compound at the Manus Island detention centre, Papua New Guinea. Credit:AAP

The doctors commissioned a statistical analysis of their findings, which concluded that at least 96 per cent of 581 refugees and asylum seekers who have applied for a medevac transfer have a significant physical ailment.

The submission has been lodged by three of the lead volunteer doctors who have been "almost exclusively responsible" for remotely assessing medical transfer applications under the medevac laws. Under the legislation, two doctors must sign off on the need for a transfer, but no Commonwealth funding is provided for the doctors.