The latest developments follow incidents earlier this year in which UK bookmakers stopped taking bets on matches featuring AFC Hornchurch, Billericay Town and Chelmsford City due to integrity concerns.
Conference South clubs were reminded by the Football Association in March "to remind their players and officials of their responsibilities under the betting and integrity rules of the FA".
Match-fixing controversies
Soccer - FA Carling Premiership - West Ham United v Crystal Palace (01 of08)
Open Image ModalIn February 1999, a Malaysian-based betting syndicate was caught attempting to install a remote-control device to sabotage the floodlights at Charlton Athletic's ground with the aid of a corrupt security officer. If the match had been abandoned after half-time, the result and bets would have stood... (credit:PA)
Selhurst Park/floodlights failure(02 of08)
Open Image ModalSubsequent investigations revealed the same gang had been responsible for previously unsuspected "floodlight failures" at West Ham's ground in November 1997 and a month later during Wimbledon's match with Arsenal at Selhurst Park. (credit:PA)
Former South African cricket captain Hansie Cronje(03 of08)
Open Image ModalCAPE TOWN, SOUTH AFRICA - JUNE 15: Former South African cricket captain Hansie Cronje raises his hand to take the oath prior to testifying before the King Commission of Inquiry into allegations of cricket match-fixing in Cape Town 15 June 2000. Cronje confessed to pocketing large sums of money during a five-year flirtation with bookmakers and vowed that he would not play representative cricket again as punishment. (Photo credit should read ANNA ZIEMINSKI/AFP/Getty Images) (credit:Getty Images)
Hoyzer Sentenced to Two Years(04 of08)
Open Image ModalBERLIN - NOVEMBER 17: Former German soccer referee Robert Hoyzer leaves court after receiving a two-year and five-month sentence November 17, 2005 on the tenth and final day of hearings in Berlin, Germany. Hoyzer took payments from a Croatian-led betting ring to manipulate four soccer matches in one of Germany's worst-ever soccer scandals. (Photo by Sean Gallup/Bongarts/Getty Images) (credit:Getty Images)
Juventus' general director Luciano Moggi(05 of08)
Open Image ModalBari, ITALY: Juventus' general director Luciano Moggi phones as he leaves the San Nicola stadium in Bari after the Italian serie A football match Reggina vs Juventus, 14 May 2006. Luciano Moggi resigned after Juventus claimed their 29th Serie A title with a 2-0 win away to Reggina on the final day of the season. (credit:Getty Images)
(06 of08)
Open Image ModalIn July 2007 it was revealed NBA referee Tim Donaghy had gambled on 10 to 15 games, including games which he officiated. Donaghy was sentenced to 15 months in federal prison. (credit:Getty Images)
Spot-fixing, 2010(07 of08)
Open Image ModalUndercover reporters from News of the World secretly videotaped Mazhar Majeed accepting money and informing the reporters that fast bowlers Mohammad Asif and Mohammad Amir would deliberately bowl no balls at specific points in England's innings.The no balls were duly bowled at the exact stages predicted, and the International Cricket Council (ICC) banned Asif, Amir and Salman Butt for terms of between five and 10 years.In November 2011, Butt and Asif were found guilty by a London court on criminal charges relating to spot-fixing. Amir and Majeed had entered guilty pleas on the same charges. All four were given prison sentences, ranging from six months to 32 months.
Snooker - Stephen Lee Filer(08 of08)
Open Image ModalStephen Lee was banned for 12 years after being found guilty of seven match-fixing charges earlier this year. (credit:PA)
Criticised for not doing more to investigate the issue, the FA say they have "worked closely" with authorities regarding the latest allegations.
An FA spokesman said on Wednesday night: "The FA has been made aware of a number of arrests in relation to an NCA investigation. We have worked closely with the authorities in relation to these allegations. The FA will make no further comment at this time due to ongoing investigations."
However, the Football League's chief executive, Shaun Harvey, said the body had not been contacted over the investigations.
"The threat of corruption is something the Football League and other football authorities treat with the utmost seriousness. The integrity of our matches and our competitions is the bedrock of the domestic game."