The curling world has been rocked by scandal at the Olympics after accusations of cheating were levelled on the ice.  (Reuters: Issei Kato)

Controversy is swirling in curling at the Winter Olympics.

The Canadian men’s and women’s teams, as well as the British men’s team, have all been accused of the same infraction: double touching the curling stone after it is released.

Here’s a look at the controversy and why it matters.

What happened at the curling centre?

On Friday, Oskar Eriksson of Sweden accused Canada’s Marc Kennedy of breaking the rules by touching the rock again after initially releasing it down the sheet of ice.

Kennedy responded with an expletive-laden outburst.

Video circulating on social media shows Marc Kennedy touching the stone after releasing the handle.(X: Umair Javid)

The Canadians won the match, 8-6.

But soon after, video appearing to show a clear double touch by Kennedy circulated on social media, taken by Swedish public broadcaster SVT.

Late on Saturday, local time, an umpire accused acclaimed Canadian skip Rachel Homan of the same infraction in a game against Switzerland.

The umpire stopped play and the stone was removed.

Homan looked shocked and denied the allegation.

Again, video spread on social media appearing to show her double touch.

Rachel Homan makes a throw during Canada’s match against Switzerland.(AP: Fatima Shbair)

Then, on Monday, in the ninth end of Britain’s round-robin game against Germany, officials said Bobby Lammie of Scotland had touched the stone after releasing it.

Here’s what the Canadians say

Asked about the footage, Kennedy said: “If somebody said to you, ‘Hey, do you double touch all the time?’ I honestly, in that split second of a moment, I couldn’t even tell you if I do or not.”

He then suggested the whole thing might have been “premeditated … to try to catch us”.

“They’ve come up with a plan to catch teams in the act,” Kennedy said.

Marc Kennedy is accuseing Team Sweden of a premeditated effort to get him penalised.  (Reuters: Eric Bolte/Imagn Images)

Homan, meanwhile, postulated that she was being unfairly targeted because of the controversy on the men’s side.

“I don’t understand the call. I’ll never understand it. We’ve never done that,” she said.

“It has nothing to do with us.”

What about video recording?

On the ice, Eriksson offered to show Kennedy a video of him double touching after the game.

But with strict rules around filming at the Olympics, some in the Canadian team turned the misconduct accusations back on Sweden.

“I was surprised that there was a live video on the hog line outside of OBS rules,” Curling Canada CEO Nolan Thiessan told reporters.

“That seems odd to me.”

Canada coach Paul Webster suggested a Swedish fan or official may have been involved in filming the hog line from the stands.

“They actually had videos for the Italian team as well. So they’ve got people up there videoing and that whole thing was premeditated and planned,” Canada’s National Post quoted him as saying.

Team Sweden has denied making any video recordings at the Olympic event.(Reuters: Issei Kato)

For their part, Team Sweden has denied any inappropriate filming, saying the video circulating on social media came from Sweden’s public broadcaster.

Eriksson said the video he was referring to when speaking with Kennedy was shot at a previous competition, not at the Olympics.

Why this is such a big story?

As fierce as the competition can be, curling has a quiet camaraderie, even though there have been scandals (see Broomgate, a sweeping-related headache World Curling believes it solved last June).

So it sticks out when there are allegations of cheating.

The Canadian team during a match against China on Sunday.(Reuters: Jennifer Lorenzini)

Canada is also the top nation in curling, easily its biggest market and where the biggest non-Olympic competitions tend to take place.

The Canadians are taking it personally that their integrity has come under attack in front of a global audience at the Olympics, which touts the values of respect and friendship.

The athletes playing for Canada and Sweden used to be close off the ice — huge rivals but admirers of each other’s skills.

Now there’s clear animosity between the teams, which is intriguing for the casual viewer but a blow to the curling community.

What’s next?

Canada’s curlers are where they don’t want to be in the middle of a Winter Olympics: on the back foot and questioning their technique.

“We’ll make some adjustments release-wise if we have to,” Kennedy said.

The team is also scrambling to be in the mix for medals at the end of the week.

Olympic curling events will continue through the week. (Reuters: Jennifer Lorenzini)

Kennedy had the worst shot success of Canada’s four players in its only game Saturday.

Canada lost 9-5 to Switzerland, a team it was expected to beat.

All eyes are on both teams now.

The Canadian men will not face Sweden again before the semifinals, should both teams make it that far, and that would be must-see TV, whether you’re a curling fan or not.

World Curling announced on Saturday two umpires would observe deliveries across all four sheets at the centre, but has since changed its stance.

“This change in protocol will see the two umpires who had previously been actively monitoring athlete deliveries remain available in the field of play, but will now only monitor athlete deliveries at the request of the competing teams,” the organisation said in a statement.

“The umpires, when requested, will monitor deliveries for a minimum of three ends.”