A senior probation officer believes high profile prisoners must be protected - even from themselves.
Shipman was found hanged in his prison cell
Harry Fletcher, assistant general secretary of the National Association of Probation Officers, said Dr Harold Shipman, who was found hanging in his cell on Tuesday morning, was not considered a suicide risk.
He said sources within the jail had told him Shipman was still being checked frequently but irregularly - roughly every hour.
He said: "It's extremely worrying that one of the most high profile prisoners in the country has committed suicide.
"If the prison authorities want to keep all high profile prisoners safe, then there are clear and substantial resource implications."
But Sir David Ramsbotham, former chief inspector of the Prison Service, said he was satisfied staff at Wakefield Prison, where Shipman was found hanged, had done all they could in assessing his safety.
He told BBC News 24 the prison was the best in the country to monitor Shipman's mental state.
He said: "I know Wakefield Prison well. It's an extremely well organised prison for looking after high security prisoners and particularly those who have some sort of mental health problems or mental disorder.
"Therefore, for him to be left off watch for 18 months must mean that the risk assessment that was carried out on him didn't show anything that suggested that he needed the high degree of a 15-minute watch".
Meanwhile the MP for Hyde, James Purnell, welcomed the announcement of an investigation into Shipman's death.
"As ever, my thoughts are with the families of Dr Shipman's victims, many of whom are still coming to terms with the loss they have suffered. I know that for many of them there will be little comfort in the news," he said.
"Until the end, Dr Shipman had neither the courage nor the honesty to admit his guilt and give what little comfort he could have to those people whose loved ones he so cruelly took away.
"The people of Hyde will recover from the tragic events Dr Shipman inflicted upon them but for many the process is far from complete."
Juliet Lyon, director of the Prison Reform Trust, said it was always a "tragedy" when prisoners took their own lives.
"High suicide rates show that the Prison Service is more often challenged in its duty to hold people safely and securely by those who attempt to kill themselves than by those who try to escape," she said.
Mark Leech, founder of ex-offenders' charity Unlock and editor of the Prisons Handbook, said that as a doctor, Shipman would be aware of the kind of symptoms suicidal prisoners would exhibit, and may have been able to mask them.
"I don't think there is any criticism that can be laid against the prison
system in this case.
"It's a tragedy whenever anyone kills themselves in prison, and that includes Harold Shipman because I prefer to look to the criminal rather than the crime."
Marjorie Wallace, chief executive of mental health charity SANE said his apparent suicide exposed the "threadbare" nature of psychiatric services in prisons.
She called on 24-hour supervision for those considered to be at risk in prisons.