ST. JOHN'S, N.L. -- NDP Leader Tom Mulcair apologized Sunday for referring to Newfoundlanders and Labradorians in a derogatory fashion during a heated exchange in the Quebec legislature nearly two decades ago.

Mulcair was in southeastern Newfoundland, where he dropped a fishing line Sunday morning to catch cod.

But he also caught criticism from a local Liberal candidate for a line he used in 1996 during a debate with a Parti Quebecois opponent over Quebec separation.

In the exchange, Mulcair, a Liberal member of the Quebec national assembly at the time, used the term "Newfie" as a synonym for "stupid," said Nick Whalen, the Liberal candidate for St. John's East.

At a news conference that followed a rousing speech to NDP supporters in St. John's, Mulcair said he regretted making the remark.

"There's no question that that was a mistake that I made in the heat of a debate 20 years ago," Mulcair said.

"I immediately withdrew it (then) because that was the right thing to do and I reiterate my apology to anyone who took offence at that."

Whalen said he didn't believe Mulcair apologized at the time for making the comment, but on Sunday accepted that the NDP leader is now sorry.

"I'll accept that, yes," Whalen said outside the hotel where just minutes before about 400 people attended a rally in support of Mulcair.

Mulcair also promised to reopen a maritime rescue sub-centre that the Conservatives closed in May 2012 and committed to ensuring that search and rescue response would be available 24 hours a day, with a maximum of 30 minutes to deploy once an emergency call is fielded.

"Banker's hours just don't work for search and rescue," he said.

The New Democrats hold two seats in the area where Mulcair was campaigning Sunday, and where he took advantage of relatively calm waters and good weather earlier in the day to jig for codfish near Petty Harbour.

The fishing village rests in the riding of St. John's South-Mount Pearl, once a longtime Conservative stronghold that turned Liberal in 2008 before flipping to the New Democrats in 2011.

Ryan Cleary, a former journalist who won the seat four years ago, is running again as the NDP candidate against Seamus O'Regan, who gained celebrity status as a national TV network morning show host.

Mulcair campaigned in St. John's East later in the day, where his party's defence critic, Jack Harris, is campaigning against Whalen and Conservative Deanne Stapleton. Harris took the seat from the Tories in 2008 and handily retained it three years later.

The NDP leader is expected to spend the first few days of this week on the East Coast before preparing for a French-language debate in Montreal on Thursday.