The man who allegedly pretended to be a doctor in New South Wales hospitals for more than a decade was well known for his lack of medical knowledge and poor behaviour, according to a former colleague.

Key points: Former Gosford Hospital colleague claims Shyam Asharya's medical knowledge was "pretty shabby"

Former Gosford Hospital colleague claims Shyam Asharya's medical knowledge was "pretty shabby" Doctor said staff "cut him some slack" because Asharya was new to the Australian medical system

Doctor said staff "cut him some slack" because Asharya was new to the Australian medical system NSW Health said the local health district had no documented complaints

Shyam Acharya allegedly spent 11 years working at hospitals at Gosford, Wyong, Hornsby and Manly under the stolen identity, Sarang Chitale.

He remains on the run with Australian authorities believing he has fled overseas.

A former colleague of Mr Acharya who worked with him as a junior doctor at Gosford Hospital in 2003 has told the ABC he was not surprised when news of the alleged fraud was made public this week.

"The moment I heard his name I remembered him," the doctor said.

"I remembered him with fear and loathing. It suddenly all made sense."

The doctor, who asked to remain anonymous, said he spent several months with Mr Acharya while they were working as junior doctors in the hospital's emergency department.

"There were at least five or six other doctors that were convinced that he was pretty shabby, that his medicine was unsavoury and that patients that he tried to hand over were not worked up very well," he said.

"I wouldn't have taken his assessments for face value. He had a reputation of being very fast and not very thorough."

NSW Health said Central Coast Local Health District had received no documented complaints and did not have any performance issues reported to them.

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Doctors 'cut him some slack'

The doctor said he found Mr Acharya to be "aggressive" and "defensive" at work, especially if anyone questioned his medical decisions.

Shyam Acharya worked for pharmaceutical giant AstraZeneca in Sydney under his false name. ( Supplied )

"A fair few of the other doctors that I was working with had similar issues to me with him and with his medicine," he said.

"But given the fact that he was new to the country and new to the Australian medical system, everyone cut him some slack."

While maintaining the training environment on the Central Coast was very good, the doctor said the workload was intense.

Asked whether he or any of the other junior doctors took their concerns about Mr Acharya further, he said it did not seem appropriate.

"It's usually left in the hands of the educator, of the supervising doctor, to decide," the doctor said.

"Everyone was so stressed just trying to get through the shift and trying to hold it together."

Acharya facing charges in court

Australian Medical Association of New South Wales president Brad Frankum said the claims are serious.

"If this is true and this doctor was not performing up to the standard that he should have, I would have hoped that that was being addressed at the time. If not, that's not good enough," he said.

"There's sometimes some leeway for junior doctors because everybody takes a different period of time to reach certain levels of competency."

Mr Acharya is now facing charges of breaching the Health Practitioner Regulation National Law in a Sydney court.

The Department of Immigration and Border Protection said it was aware of visa fraud allegations, and investigations were underway.

Mr Acharya's former colleague said he was surprised just one complaint had been made about the man's work so far.

"I'm sure there were more," he said.

"The medical fraternity rarely ever accepts any complaints as genuine. It goes to show just how perfectly the system works."

But he stressed the importance of not vilifying those from foreign backgrounds.

"It's easy to find a scapegoat as the foreign doctor, when really the same holds true for Australian doctors," he said.

"There's a lot of bad apples that are Australian-trained and Australian born and that do not perform to Australian standards."

Mr Acharya later worked for one of the world's leading pharmaceutical companies, AstraZeneca.