A half-time dressing room bustup inspired France to come back and win their Euro 2016 match against the Republic of Ireland on Sunday, two goal hero Antoine Griezmann said.

"We had a bad first half but a few things were said at half-time," Griezmann said of the heated exchanges between the tournament hosts who fell behind to a Robbie Brady penalty just 90 seconds into the game when Irish striker Shane Long was fouled by Paul Pogba.

"It was stormy," added the Atletico Madrid striker who hit two goals in four minutes after the clear-the-air break.

"In the second half, we were more like a team which wanted to fight until the end."

Griezmann dragged France back into the game, nodding in the equaliser before driving in a second goal to propel his team into the last eight and a meeting with either England or Iceland.

"I can raise my voice at half-time," said French coach Didier Deschamps.

"We needed to keep things calm, but also shake things up a bit.

The players all got involved in the break, some of whom were on the pitch, they had their part to say in what was said."

Griezmann said the penalty, the second quickest goal in Euro history, had shaken France.

"We were all shouting each other on after the penalty and we knew we had to improve," he said.

Griezmann's strike partner Olivier Giroud said France had had to throw caution to the wind in the second half.

"The match was going in their favour (Ireland's) so we told each other that we mustn't have any regrets and that we had to lift our game," the Arsenal forward said.

Deschamps said France got better when they shook off the early tension and went "a bit crazy".

"Sometimes it's difficult. When you concede a penalty at the start of a match it made us tense and the Irish can play a bit," Deschamps said.

Deschamps said the three tight last-16 matches on Saturday, two of which went to extra-time, showed there are no easy games in the tournament.

"It was hard for us too, but mission accomplished," he said.

"You shouldn't be too calculated. The players need discipline but sometimes we're better when we go a bit crazy.

"We really speeded things up and that's when we are most dangerous."

A lot of that speed was added by Kingsley Coman, who was introduced at half-time, and Griezmann said he was delighted with the tactical change.

"The manager brought Kingsley Coman on and he caused some damage. I was closer to the striker and the penalty area," Griezmann said.

"I hope we continue that way."

France will switch to the Stade de France in Paris when they go in search of a semi-final place next Sunday.