RCMP say they have stepped up security on Parliament Hill in response to a protest by Greenpeace activists who scaled the centre and west blocks of the Parliament building Monday.

The protesters draped the building with banners advocating government action to combat climate change.

Following the protest, Ottawa police said they arrested 19 of the protesters who had climbed on the buildings and one organizer on the ground.

In a written statement, the RCMP said they have increased security measures pending a full review of what happened.

The results of the review will be watched carefully by Public Safety Minister Peter Van Loan, his office said Monday.

The Liberal critic for public safety, Mark Holland, said the Greenpeace action was inappropriate.

"There's a balance," Holland said. "We've got to make sure this [Parliament Hill] is as open as possible. But, by the same token, we don't want to see a situation like this get to the point that it did before there is intervention.

""It might be because there are a number of different jurisdictions that have responsibility for providing security in the House. We're going to have to take a look at doing a better job of co-ordinating the various security functions that are there."

Holland said Greenpeace's message was lost because of the nature of the stunt.

Security on Parliament Hill has been increased ever since the Sept. 11, 2001, terrorist attacks in the United States.

RCMP cars guard the entrances to Parliament Hill and patrol the grounds.

Anyone entering the Parliament building must go through at least one metal detector. Surveillance cameras cover most areas.

Only authorized vehicles are allowed on the Hill, and parking in the nearby lots is restricted.

Even tougher security is the likely outcome of Monday's protest. Every time Parliament Hill security is threatened, the RCMP take steps to make sure such breaches don't occur again, said RCMP spokeswoman Cpl. Caroline Poulin.

"It's an incident the RCMP is taking very seriously," she said.