An Australian judge has ordered seven years in jail for an Indian-born surgeon who was convicted this week of killing three patients and grievously harming another during botched and unnecessary operations.

Jayant Patel, nicknamed "Dr. Death" by Australian media, must serve at least three-and-a-half years before being eligible for parole. Relatives of his victims said they were satisfied the sentence will prevent him from doing more harm.

A government study had implicated Patel in 13 deaths at a hospital in Queensland, where he worked from 2003 to 2005. Previously, he had been disciplined for negligence by medical authorities in two American states, New York and Oregon.

The prosecutor said at Thursday's sentencing hearing there was no record of a worse case of medical criminal negligence in Australia.

Some information for this report was provided by AP and AFP.