Tennis is facing more questions about its integrity after it was revealed two officials have been banned for corruption offences and four more are currently suspended.

The International Tennis Federation has confirmed a story published by the Guardian - the first time the sanctions had been made public.

Kirill Parfenov of Kazakhstan was banned for life in February 2015, after making contact with another official on social media in a bid to manipulate match scoring.

Croatian Denis Pitner was suspended for a year last August after passing on fitness details of a player to a coach and accessing a betting account from which tennis bets were placed.

The Guardian story about the two international umpires being banned follows BBC and BuzzFeed allegations about match-fixing at the top level of the sport that overshadowed the start of the Australian Open last month.

Those reports led to the announcement of an independent review into tennis' anti-corruption practices, which are overseen by the Tennis Integrity Unit (TIU).

The newly-reported offences are said to have taken place on the Futures Tour, the lowest rung of professional tennis.

In a joint statement on Tuesday, the TIU and ITF said: "Kirill Parfenov of Kazakhstan was decertified for life in February 2015 for contacting another official on Facebook in an attempt to manipulate the scoring of matches.

"Separately, Denis Pitner of Croatia had his certification suspended on 1 August 2015 for 12 months for sending information on the physical well-being of a player to a coach during a tournament and regularly logging on to a betting account from which bets were placed on tennis matches.

"The decision to sanction both officials under the ITF code of conduct was taken following TIU investigations. This approach is being reviewed as part of the recently announced independent review of integrity in tennis that will be chaired by Adam Lewis QC."

The statement added: "To ensure accuracy of reporting, four officials are currently suspended pending the completion of ongoing investigations by the TIU. In order to ensure no prejudice of any future hearing we cannot publicly disclose the nature or detail of those investigations. Should any official be found guilty of an offence, it will be announced publicly."

The most damning aspect of the recent match-fixing allegations was that authorities had not investigated properly - a charge strenuously denied by the TIU.

Tennis has been accused of a lack of transparency in its anti-corruption measures, and these latest revelations will provide fuel to the sport's critics.

In their statement, the TIU and ITF explained the bans were not made public because the officials were sanctioned under the ITF code of conduct for officials.

"Previously, the ITF Code of Conduct for Officials did not allow public dissemination of officials sanctioned," they said.

The code was amended in December 2015 and sanctions issued from now on will be announced.

The names of players and officials punished under the Tennis Anti-Corruption Programme are announced publicly, with Frenchman Morgan Lamri the one official to have been handed a life ban so far.

The ITF signed a lucrative deal with data company Sportradar in 2012, which was extended last year, to provide live scoring at low-level tournaments.

That enabled betting companies to offer markets on matches at those tournaments.

The technology involves umpires updating the score after each point, and the Guardian alleges corrupt officials were deliberately delaying their updates to enable gamblers in the know to take advantage of favourable odds.

The ITF and TIU defended the partnership with Sportradar, arguing it helps prevent corruption rather than facilitate it.

"The ITF's data contract with Sportradar for an official data feed provides regulation and control where previously there was none," said the statement.

"Our agreement with Sportradar, like those in place with ATP and WTA, by creating official, accurate and immediate data, acts as a deterrent to efforts by anyone trying to conduct illegal sports betting and/or unauthorised use of data for non-legal purposes.

"Sportradar are excellent partners and share with the ITF the goal of ensuring the integrity of our sport."