TORONTO - A group opposed to Porter Airlines' proposed expansion plans for the Billy Bishop Toronto City Airport says boaters and marine shippers should be concerned.

NoJetsTO points to a report that says existing safety zones around the airport would have to be expanded if Porter is allowed to use jet aircraft.

A report by Transport Action Ontario -- a public transport advocacy group -- says the changes would require a major expansion of the safety zones around the airport, impacting marine activities.

The report, released Thursday, says introduction of Bombardier CS100 jets to the airport would require a runway extension of at least 168 meters at each end.

It says that unless exemptions are granted, Transport Canada's minimum requirements would result in exclusion zones that would be a severe impediment to recreational boating, Toronto Island ferry routes and lake shipping.

The report recommends that Toronto defer a decision on the airport expansion until Transport Canada has reviewed and approved the airport design.