Marcus Shane Solomon was found guilty of 10 charges of sexual violation, rape and kidnap at a jury trial in February.

A rapist deemed too obese for prison will cost taxpayers at least $1250 each day he spends in hospital.

That's more than four times the $300 daily cost of keeping an inmate behind bars.

Marcus Shane Solomon was last week sentenced to eight years and four months' imprisonment for raping and sexually abusing three young girls in Kaikōura in the 1980s and 1990s, when he was aged between 14 and 22.

He appeared in court by audio visual link, lying on a hospital gurney.

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​His health had deteriorated since his trial in February – when a jury found him guilty of 10 charges of sexual violation, rape and kidnapping – and he ended up at Burwood Hospital in Christchurch, "virtually immobile" with complications from morbid obesity including a serious infection and back problems.

Because prison hospitals did not have the resources to provide for his medical care, Judge Zohrab jailed him to hospital until he reached a healthy weight.

The average daily bed rate at Burwood Hospital is $1250, depending on the patient's needs, a Canterbury District Health Board spokeswoman said. Specialist care or additional doctor or nurse care was on top of that.

Chief custodial officer Neil Beales said Corrections had a "duty of care" to ensure prisoners received the same healthcare as anyone else.

Some prisoners had health concerns prison staff may not manage, Beales said.

A prisoner could be in Corrections custody at a hospital or other facility, could transfer to a secure facility, or could apply to the New Zealand Parole Board for compassionate release, Beales said.

National Party Corrections spokesman David Bennett said Solomon's situation was "entirely of his own making" and he "shouldn't be allowed to take taxpayers for a ride" indefinitely.

He said Solomon should be required to reach a healthy weight by a certain date, then be sent to prison - regardless of whether he met it.

"He committed heinous crimes against young women and he allowed himself to get to an unhealthy weight, yet it's taxpayers who are having to foot the extra cost of him being in hospital rather than prison, which is where he should be."

Corrections Minister Kelvin Davis declined to comment.

Solomon is the son of Whale Watch founder and Takahanga Marae upoko (leader) Bill Solomon.

Marcus Shane Solomon told a probation officer the allegations agains him were borne from a long-standing conflict between he and the victims' families, and claimed a conspiracy of "politics linked to Māori health providers", Judge Zohrab said at sentencing.