The tennis world has been rocked by yet another scandal after the Guardian reported that some umpires have been disciplined or are under investigation over suspicions of colluding with betting syndicates.

On Tuesday, the Guardian reported that an umpire from Kazakhstan had been banned for life in February 2015 for attempting to convince another official to help skew the results of tennis matches on the International Tennis Federation (ITF) Futures Tour, the lowest rung on the pro tennis ladder.

The Guardian also revealed that the ITF had slapped a 12-month suspension on a Croatian umpire last August for logging onto a betting account that was used to wager on tennis.

In a worrisome development, four other umpires currently under investigation had been tasked with relaying real-time match results to sports data company Sportradar, which supplies information to bookmakers around the globe and which just extended its partnership with the ITF in December.