Johnny Sexton set a new points record for his country as an efficient Ireland dominated Tonga to secure a 59-16 bonus-point victory and consolidate top spot in World Cup Pool B.

Ireland scored four first-half tries at the Stade de la Beaujoire and four after the break to see off the Pacific islanders, who were playing their first game of the tournament in France but, despite the inclusion of several former All Blacks in their lineup, proved no match for the top-ranked team.

The 38-year-old Sexton only played the first half but scored a try, a penalty and four conversions for a 16-point tally that took him to 1,090, going past Ronan O'Gara's record of 1,083.

Ireland's first three tries came from Tadhg Beirne, Caelan Doris and Mack Hansen before an obviously delighted Sexton went past the record by dotting down between the posts to open up a 31-13 lead at the break.

Bundee Aki scored twice in the second half and James Lowe and Rob Herring also crossed to extend Ireland's lead.

Tonga scored their try on the stroke of halftime through Vaea Fifita and flyhalf William Havili, whose elder brother is in the New Zealand squad, did not miss any of his kicks to notch up 11 points.

Ireland attacked spaces left by Tonga's propensity to over concentrate their defensive line and breaks through the middle set up the tries for Beirne and Sexton.

Doris' 26th-minute effort came off a driving maul and Hansen jinxed his way off the touchline on the right wing for a sparkling try.

Ireland made multiple changes early in the second half nbefore again breaching Tonga's line with Lowe looping around to finish off another strong driving maul.

Aki hit the line at speed to burst through a gap and sprint away for their sixth try and he grabbed another soon afterwards.

Herring added Ireland's eighth try just before the final whistle to allow Sexton's replacement Ross Byrne to put over his fourth conversion.

Coach Toutai Kefu admitted his Tonga side had been totally outclassed in their World Cup opener but hoped they could land a few more punches in Pool B.

Tongan hopes of making an impact in France had been high after drafting in a handful of former All Blacks to their squad but the 59-16 loss in Nantes was a numbing reality check for the Ikale Tahi.

"Honestly, too good for us. Very clinical, that's why they're the best team in the world," said Kefu, a World Cup winner with the Wallabies in 1999.

"We're disappointed. We'll regroup and see what we can salvage out of this performance."

Tonga skipper Ben Tameifuna said the fact Ireland had already played a World Cup match while the Pacific islanders were kicking their heels in their Paris training camp might have been a factor.

"There were a few boys on the team that were playing their first game tonight in the World Cup and I think it's an eye opener as to what it takes to play at this level," he said.

Tonga looked competitive for large periods of the game and were in touch on the scoreboard until Ireland scored three tries in 11 minutes before halftime.

Former All Black Vaea Fifita scored a try during a period of intense Tongan pressure just before the break but backs like Charles Piutau and Malakai Fekitoa were unable to find the space to show their class.

They had also hoped to make the scrum a weapon but the precision of the Irish in all areas of the game helped negate the power of the Tongans.

"We're going to take the learnings and move forward," the 150kg Tameifuna added.

"There were plenty of positives but plenty of one-percenters that we need to work on."

The path does not get any easier for the Tongans with matches against in-form Scotland and world champions South Africa before their final pool match against Romania.

"We'll dissect this game, we'll regroup. We're still in this competition," added Kefu.

"Hopefully, we'll be able to throw a little bit more punches next week."