Professor Maitz said he has examined and treated patients who were burned after pouring accelerant on themselves, and in his experience they poured the substance over their heads before setting it alight. He said this made the absence of burns on Ms Kaur's head and face "unusual".

"In my opinion the accelerant has been poured or thrown on her by others," Professor Maitz said.

"Having treated dozens of patients that went through this unfortunate event, the vast majority survive and the vast majority have deep burns on the scalp and face, because that's where the liquid ignites first."

Professor Maitz prepared a report after examining photographs of burns to Mr Singh's hands, which were taken hours after the blaze. He described Mr Singh as having partial thickness burns and blisters on some fingers.

He said the palms of both hands were mainly uninjured, which suggested Mr Singh's palm was protected "either by him making a fist or holding something". Professor Maitz said if Mr Singh had been attempting to put out the fire by patting Ms Kaur, "he would have had more extensive burns to his palms".

Defence barrister Margaret Cunneen, SC, asked Professor Maitz if the vast majority of suicide victims by burning in Sydney were of Indian, Pakistani or Sri Lankan background.

"Yes," Professor Maitz said.

Ms Kaur migrated to Australia from India in 2006 after marrying Mr Singh.

The jury was earlier told that the suspected ignition point of the blaze was the laundry of the home, where a lighter was found on the floor and a five-litre fuel container was discovered in the closed cupboard with its lid on.

Both objects had Ms Kaur's fingerprints on them, but not Mr Singh's.

In the minutes before the blaze, Ms Kaur called triple zero and gave her address, then said: "My husband nearly kill me". She was asked what happened, but the call terminated before she offered any further detail.

The trial continues.