Under the regulation, people within five metres of the security area can be asked to identify themselves to police and state the purpose of their visit on request. ((Mike Segar/Reuters))

Ontario Premier Dalton McGuinty will not explain why his cabinet passed a secret law giving police more power to arrest people during the G20 summit in Toronto.

Opposition critics and civil libertarians are outraged the Liberal cabinet not only gave police extra powers to question, search and detain people in the week leading up to the summit, but that they also kept it secret.

The regulation, which took effect June 21 and expires Monday, effectively expands the jurisdiction of the existing Public Works Protection Act to apply to the entire fenced perimeter around the Metro Toronto Convention Centre, where the summit was held this weekend. It does so by designating the barrier that encircles a large chunk of downtown around the convention centre as a public work.

The act stipulates that anyone entering a public work is obliged to give police their name and state the purpose of their visit on request. Anyone who fails to identify themself or explain their presence can be arrested and fined up to $500 or sentenced to jail, and anyone in an area designated as a public work can be searched.

McGuinty's cabinet passed the regulation quietly on June 2 with no debate in the legislature.

McGuinty's office said the premier will not be available to respond to questions about the need to pass a law that critics say suspended civil liberties in downtown Toronto without telling anyone.

Instead, the premier's office referred reporters to a newspaper ad with the headline: What you need to know about the G20 summit.

The ad talks about restrictions to people who want to enter the secured summit area, but it makes no mention of the special powers given to police to arrest people during the G20 week.

The Canadian Civil Liberties Association said the secret regulation was a factor when police decided to make mass arrests and search people's bags thoughout downtown, even well away from the summit perimeter, after cars were set on fire and windows smashed Saturday.

With files from CBC News