LONDON, Ont. - Outrage among Canadians that notorious child killer Clifford Olson is receiving a public pension while in prison is completely justifiable, Prime Minister Stephen Harper said Thursday.

Harper called the notion of serious offenders receiving such tax dollars in custody upsetting, and said he wants the practice stopped.

"I've read all the recent stories in the papers about Mr. Olson, and I must admit that I'm as upset about this, as concerned about this, as any other Canadian," Harper said.

"This is a situation that I think has many Canadians upset, and for good reason."

Olson killed at least 11 boys and girls before he was imprisoned for life in 1982.

He turned 70 this year, and as a senior citizen, is entitled to Old Age Security and Guaranteed Income Supplement.

The money has been going into a trust fund for Olson, who is serving his sentence of 25 life sentences in a maximum security facility.

The programs pay the killer, and several hundred other convicts currently behind bars, more than $1,100 a month each.

Word of the pension payments has sparked anger among victims' rights groups.

Harper said it's not surprising the issue has only now come to the forefront.

"Probably the reason that this hasn't arisen before is that this is unusual; these are unusual circumstances," Harper said.

"It is not typical that we have senior citizens facing life incarceration."

Harper said he has asked Human Resources Minister Diane Finley to look at ways to change the system to ensure prisoners don't benefit from the pension plans.

"I've instructed the minister to look at what options are available to us to rectify the situation because it should be rectified," Harper said.

Harper did not comment on whether families of Olson's victims should have any claim to the money he has received from the federal government.

On Wednesday, Finance Minister Jim Flaherty also called the issue "worthy of review."

British Columbia's solicitor general, Kash Heed, has also expressed outrage, and called for an end to such benefits for criminals like Olson, who carried out his murders in B.C.

Olson has never shown any remorse for his horrific crimes. He claims to have killed others but was not caught for those crimes.

RCMP paid him $100,000 to lead them to the bodies of his victims, but that money was later put in trust for his estranged wife and son.