LONDON • An umpire secretly banned for a year by tennis authorities for betting offences was immediately allowed to work at some of the world's biggest tournaments, according to The Guardian.
Denis Pitner, a Croat who was suspended last August after regularly logging on to a betting account from which bets were placed on matches, was a line judge at the US Open, one of tennis' four Grand Slams, later the same month.
He was also judging at an event in Doha last month which featured Novak Djokovic and Rafael Nadal.
The United States Tennis Association (USTA), which runs the US Open, said it was "shocked" to be told the news by The Guardian - and blamed the mistake on a flaw in its processes and Pitner being placed on the banned list just a day before the Open started on Aug 25.
A spokesman told The Guardian: "As we have now determined, Denis Pitner had been approved to work the US Open as a linesman on July 13. The USTA was notified that Mr Pitner was placed on the 'do not credential' list on Aug 24.
"Mr Pitner had already picked up his credential prior to the USTA being notified. Due to a flaw in our process, which we are investigating now, Mr Pitner's credential was not cancelled. For this reason, he did work as a linesman at the 2015 US Open."
The USTA spokesman confirmed that Pitner had worked in the qualifiers and then the main draw at the US Open until Sept 10.
He also insisted that the mistake would be urgently investigated, adding: "The USTA takes this matter extremely seriously and has made the investigation of what caused the error its highest priority.
"We will also work with the newly-created independent review panel to ensure instances such as this are not repeated in the future."
The Association of Tennis Professionals, which runs men's tennis, blamed a "breach in procedures" for Pitner being allowed to work in Doha.
A spokesman confirmed it would also review the issue to ensure this did not happen again.
This latest news will heap more embarrassment on tennis authorities, following a Guardian investigation that earlier this week revealed that four umpires had been secretly suspended for allegedly taking bribes from betting syndicates.
Another umpire, Kirill Parfenov from Kazakhstan, was also secretly banned for life in February last year.