Prime Minister Stephen Harper says a "horrific" oil spill similar to the one in the Gulf of Mexico couldn't happen in Canadian waters because of the federal government's strong offshore drilling rules.

Harper's defence of Canada's drilling protocols came after NDP Leader Jack Layton called on him to convene an emergency meeting of G8 environment ministers to put the Gulf spill on the agenda for this summer's G8 summit in Muskoka, Ont.

During question period Monday, Layton said the catastrophe in the Gulf will have an impact on the environment for decades to come and "people all over the world are very concerned" about the environmental risk of similar offshore drilling.

Calling the Gulf oil spill "an environmental catastrophe unlike anything we've seen in quite a long time," Harper heaped criticism on BP — the operators of the rig that exploded and burned on April 20, killing 11 workers and triggering the massive leak of about 800,000 litres daily.

"The behaviour of the companies in question is completely unacceptable and would be completely unacceptable in this country," he told the House.

But Layton cited BP's recent acquisition of three licences in the Beaufort Sea for more than 6,000 square kilometres of drilling rights and said the company was trying to weaken the environmental requirements for drilling in the region.

"BP failed to prevent the worst ecological disaster since the Exxon Valdez, and now they want to have their way with our Arctic?" Layton said.

Harper said the National Energy Board doesn't allow for offshore drilling unless the safety of workers and the environment are protected — and that won't change.

"That is the bottom line of this government, and we will not tolerate the situation that we see in the Gulf of Mexico," he said.

Oil and gas companies that want to drill in the Arctic must first get regulatory approvals from the National Energy Board. To do that, they must show they will drill relief wells in case of an accident or provide an alternative safety plan.

Oil companies have argued relief wells in the North are not practical, since it would take too long to drill them if there is an accident. But oil industry critics have said the Gulf spill should raise warning flags in Canada, especially about the need for relief wells.

Layton also said Harper should "show some leadership" and heed the call of Nunavut's land claims organization, Nunavut Tunngavik Inc., for a marine safety conference to address the issue.