NSW Corrective Services has refused to foot the bill for serial killer Ivan Milat's cremation, prompting his brother to demand his body be dropped back at the jail for "them to sort".

Bill Milat said his brother's final wish was that he "not pay a cent" for the funeral and said he would be honouring that wish.

Left: Ivan Milat leaving hospital earlier this month. Right: Bill Milat with his wife Carol at their home in the Southern Highlands. Credit:Nine, Sylvia Liber

In a letter dated October 24, Milat, describing himself as "pretty crook", said: "Please don't pay for any funeral service or contribute in any way. Corrective Services NSW to fund it all, a pauper burial or whatever is suitable.

"I have advised the Commissioner of Corrective Services NSW of my wishes."