Ontario's Liberal government has earmarked $5.5 million to advertise cuts to hydro bills -- ads the opposition says use public money to make the Liberal party look good.

In response to a freedom of information request by the New Democrats, government documents cite "negative media coverage" of rising electricity costs as a key piece of context for why the advertising campaign is needed.

"Despite recent cost reduction actions the government has implemented, the overriding messaging from media has been unreasonably high costs associated with electricity," says the project brief, dated Feb. 2 -- after bills were reduced by eight per cent, but before the government announced a further 17 per cent cut.

"The value of what people are getting for their money has been overshadowed."

About $2.5 million is allocated for the fiscal 2016-17 year and a further $3 million is set aside for the following year, the documents show. About $1.2 million had been spent as of March 31.

A set of radio ads this year have told listeners that people would receive an average of 25 per cent off their hydro bills this summer and rate increases are being held to inflation for four years.

Auditor general Bonnie Lysyk has said the ads likely wouldn't have been approved under previous government advertising rules because the intent is to convey a positive impression of government.

Lysyk has complained that changes the Liberals enacted to government advertising legislation in 2015 reduced her office to a rubber stamp.

The old rules banned ads as partisan if the intent was to foster a positive impression of government or a negative impression of its critics, but the new rules say an ad is partisan only if it uses an elected member's picture, name or voice, the colour or logo associated with the political party, or directly criticizes a party or member of the legislature.

Energy Minister Glenn Thibeault said the ads are necessary to inform people about bill reductions so they can adjust their household budgets.

"Still people don't know about the 25 per cent reduction," he said. "They were having a hard time, as they said before, choosing between heating and eating and so now as we're moving forward into those winter months they can plan for this."

But NDP Leader Andrea Horwath says people can tell their bills have gone down simply by looking at them.

"The $5.5 million should be invested in helping people get their hydro bills down, not in partisan government advertising that wouldn't pass the smell test if the government hadn't changed the laws," Horwath said.

Progressive Conservative Leader Patrick Brown said the government has "completely abused the public trust" when it comes to public advertising.

"You're supposed to use government advertising for a broader good," he said. "What we don't need is partisan vanity ads using taxpayer monies to advance the interests of the Liberal party."

Part of the Liberals' hydro plan is increasing the benefits available under the Ontario Electricity Support Program for low-income ratepayers, which Thibeault cited as another reason the advertising is important, because the program requires people to sign up.

But despite the advertising so far, not as many eligible people have signed up as the government was hoping.

Thibeault estimated that 500,000 people would be eligible, but his office said that 232,115 customers are benefitting.

"We're seeing the numbers increase month to month and that's something, I think, for us to be pleased about, but I'd still like to see more people sign up for it," he said.

Canada Revenue Agency requirements mean that people need to enrol in the program with a physical signature on paper, instead of just via the internet, but Thibeault said the government is working with the CRA "to find ways to help with that." As well, the government is working to automatically qualify people on welfare or disability, he said.

The low-income benefits were increased as part of the hydro plan, so that someone who qualifies for the smallest credit -- a single person earning less than $28,000 -- would save $45 a month instead of $30.