Canterbury prop Ryan Tandy declared he had "nothing to hide" on Friday after he gave away a penalty that has been the key focus of a betting probe from last weekend's NRL match between the Bulldogs and North Queensland.

The NRL are investigating a number of unusual bets before the game, some involving four figure sums, placed on the Cowboys to register a penalty goal as the first points of the match.

Tandy firstly turned over the ball from the opening kick-off and then was involved in laying on a Cowboys player in a play-the-ball, resulting in the home side being awarded a penalty directly in front of goal.

The Cowboys opted not to take a shot at goal, instead taking a tap and ultimately scoring a try.

Tandy told the Nine Network on Friday that he'd had no idea about the betting plunge and had not done anything untoward.

"To be saying I was involved in something like that is ridiculous," he said.

"To be honest, I haven't even had a look at the vision, that's how much I was unaware of it.

"All I knew is that I cost the team a try at the start of the game.

"Obviously you are not allowed to bet on rugby league for a start being a rugby league player, so there is no way I would do that. Second of all I would never ever jeopardise my team like that anyway."

Tandy said if he was approached by the NRL regarding the incidents he would have "nothing to hide".

Bulldogs chief executive Todd Greenburg said the club would help the NRL in any investigation.

"We have been made aware of it from the NRL over the last few days," he said.

"Our understanding is they are investigating and we've said to them we'll cooperate in any possible way to get to the bottom of the information."

The NRL said it could question players and call for TAB footage as they continue to probe the betting plunge.

NRL media and communications director John Brady said on Friday investigations were ongoing, with the league in possession of some betting sheets provided by bookmakers.

Asked if players may be interviewed and security footage of people placing bets in TABs requested, Brady said: "all those things are possible".

"We're not going to say what we're doing and what we're not, right now we're just looking into some bets.

"All those options are open."

TAB Sportsbet's Glenn Munsie, the man who tipped officials off to the plunge late on Saturday afternoon, said the matter was now in the hands of the body's regulatory and compliance section who are cooperating with the NRL.

"It's now out of our hands but it's certainly not a real good look," he said.

Munsie alerted the NRL to the betting plunge a few hours before the game, which had no bearing on the finals.

"I rang (John) Brady about 5.30-ish on Saturday to tell him we'd suspended betting which is an arrangement we have with the NRL," he said.

Munsie said if the NRL asked for footage from TAB outlets, and it was available, they would probably provide it.

He said bets on a Cowboys penalty being the first scoring play were placed in agencies in different states for three days.

"Whether that was people just following hunches, you don't know," he said.

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