The Ontario Attorney General's Office is challenging an order from the privacy commissioner that the government release the legal costs of its court battle with families of autistic children.

A day before the deadline requiring the data to be released, the attorney general's office requested a judicial review and a stay of the commissioner's order.

New Democrat MPP Shelly Martel has spent three years trying to uncover the cost of the court case, in which families asked the province to continue funding expensive therapy after their children reach age six.

At a news conference at Queen's Park on Tuesday, Martel accused the Liberal government of using "litigation chill" to "muzzle" her and hide how much the dispute has cost taxpayers.

Ontario's Court of Appeal ruled in 2006 that the province does not have to pay for specialized autism treatment for children age six and older. The government had appealed an earlier court ruling in favour of a group of parents asking for the province to pay for the treatment past that point.

Martel said the government has refused all her requests, including those made under the Freedom of Information Act, for the costs of that case, citing solicitor-client privilege.

As a result, Information and Privacy Commissioner Ann Cavoukian became involved and ruled earlier this year that the government should release information on the legal costs.

"This decision to take legal action against me and against the information and privacy commissioner is obscene and makes me very angry," Martel said.

The MPP said the legal action shows the government will go to any length to keep the court costs a secret.

"It's clear that the Liberals are happy to squander even more money on lawyers and process — money that could be spent, for example, to provide IBI [intensive behavioural intervention] treatment to autistic children."

Martel vowed to continue pursuing the information, saying: "I'm not going to give up and I'm not going to go away."

She has hired a Toronto lawyer to fight the government's action.

With files from Canadian Press