TORONTO - Ontario's premier 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, but that they also kept it secret.

Dalton McGuinty's office says 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 says the secret law was a factor when police decided to make mass arrests after cars were set on fire and windows smashed Saturday.