Three people are in custody and being questioned by police in connection over football spot-fixing allegations.
The National Crime Agency, which is working closely with the Football Association and the Gambling Commission, confirmed it had launched its investigation after being contacted by the Sun on Sunday.
As part of its investigation, the Sun on Sunday recorded footage that appears to show players allegedly arranging spot-fixing.
Ex-Portsmouth defender Sam Sodje allegedly claimed he could arrange a yellow card booking in the Football League, in exchange for tens of thousands of pounds.
The former Premier League player and Nigerian international also allegedly told how he punched an opponent in the groin during a game earlier this year to get sent off in exchange for a £70,000 payout.The Sun on Sunday
And he claimed he could rig Premier League games, and even said he was preparing to fix matches at next year's World Cup in Brazil.
Another player, Cristian Montano, for Oldham Athletic appears to explain in the video how he attempted to get booked during a match against Wolves, in return for cash.
The ex-West Ham player said: "From minute one I was hacking people down.
"People running past me and I would go clip.
"I run against one player and barged him."
Football League chief executive Shaun Harvey, said: "We treat any allegations of criminal activity in our competitions with the utmost seriousness.
"Given that there is an ongoing police investigation into this matter, we cannot comment further at this time.
"Although, we would encourage anyone with any evidence to report it to the police.
"We will be giving our full assistance to the police during their investigation."
The NCA said an active investigation is now under way.The National Crime Agency is investigating separate fixing claims
A spokesman said: "Three people are in custody and are being questioned by NCA officers. We cannot comment further at this stage."
In a statement, Portsmouth Football Club said: "If these serious allegations are true, then we are extremely shocked and saddened by them, as match-fixing of any type goes to the heart of the integrity of the game.
"The player in question no longer plays for the club and we have not been contacted by the authorities, but of course we would cooperate fully with any inquiry."
The new probe comes after the NCA announced at the end of last month that it had launched a separate investigation into "a suspected international illegal betting syndicate".
Gambling on the matches is thought to have taken place on Asian-based betting services and so far investigators to do not believe British betting markets are involved.
That inquiry was launched after an undercover investigation by the Daily Telegraph newspaper, which recorded one alleged fixer offering to rig two games.
It is understood to involve clubs in the English Football Conference, the level below the Football League.
On Thursday, the NCA revealed that two footballers from Brighton-based Conference South team Whitehawk FC had been charged over match-fixing allegations.
Michael Boateng and Hakeem Adelakun, both 22 and from the Croydon area of south London, were charged with conspiracy to defraud contrary to common law.
The two men have been bailed to appear at Birmingham Magistrates' Court on December 11.
They are the third and fourth people charged to date in connection with the NCA investigation into the alleged international illegal betting syndicate.
Chann Sankaran, 33, from Hastings, East Sussex, and Krishna Sanjey Ganeshan, 43, from Singapore, were charged on November 28 with plotting to defraud bookmakers.
Both were remanded in custody to appear at Birmingham Crown Court on December 13.
Sky News sports presenter Charlie Thomas said both NCA investigations were being carried out separately.
He added: "This is a situation that football has been fearing and had hoped it had nothing to do with football at all, but now it appears it is encroaching on the league as well as the non-league."
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