An independent review of corruption in tennis found that the sport "faces a serious integrity problem" at its lower levels — a "tsunami," according to one person interviewed — but did not determine there are widespread problems at ATP, WTA and Grand Slam tournaments.

The report released Wednesday showed no cover-up by tennis' governing bodies of improper betting or match-fixing, although there were "errors made and opportunities missed," Adam Lewis, a member of the three-lawyer review panel, said at a news conference in London.

Recommendations included putting an end to the International Tennis Federation's sale of official live scoring data to betting companies, which creates an environment that encourages corruption; increasing transparency by making public the tournament appearance fees paid to some players; and expanding the staffing and reach of the Tennis Integrity Unit (TIU), the anti-corruption group established in 2008 after a surge of suspicious betting activity.

"Fundamental reform is required," Lewis said.

He said there were "shortcomings in the sport's efforts to address the long-standing, underlying causes of breaches."

Lewis added: "In a number of instances, the ATP failed to exhaust potential leads before ending investigations."

The panel called this an interim report and said a final version would be issued later this year.

The review was called for after the BBC and BuzzFeed News published reports in January 2016, alleging that tennis authorities ignored widespread evidence of match-fixing involving more than a dozen players.

The panel surveyed more than 3,200 tennis players and interviewed 200 others involved in the sport. While Lewis said the work discovered a "lamentably fertile breeding ground for breaches of integrity" at less-prominent Challenger and Futures events, there "appears to be much less of a problem at the tour and Grand Slam levels."

The report cited one TIU investigator as estimating that "hundreds of matches at Futures level (both singles and doubles) are not being played fairly, with the numbers reducing as you move upwards through the ranks of the professional game." Another investigator, according the report, "reported that at the lower levels of the sport, tennis faces a 'tsunami' of low-level betting and other integrity breaches."

It said the TIU needs to increase its staffing — as of now, it does not employ tennis or gambling experts, for example — and needs to be "entirely independent," including being housed separately from the ITF and having regular external audits.

A joint statement issued Wednesday by the ITF, ATP, WTA and the four Grand Slam tournaments — the Australian Open, French Open, Wimbledon and U.S. Open — acknowledged "that there are vulnerabilities, particularly at the lower levels of tennis" and pledged to "address these concerns through firm and decisive action."

Those governing bodies said they agree "in principle" with reforms proposed by the review.

A major cause of problems, according to the report, is the live scoring data made available since 2012.

"Whilst these deals have generated considerable funds for the sport, they have also greatly expanded the available markets for betting on the lowest levels of professional tennis," the panel wrote. "The ITF did not appropriately assess the potential adverse effects of these agreements before entering into them."

The report also calls for eliminating all sponsorship deals with gambling companies; currently, players can't enter into such agreements, but individual tournaments can.

Lewis noted that at lower tiers of the sport, where prize money can total $15,000 or $25,000 at a Pro Circuit tournament, it can be difficult for players to earn a living, which makes corruption more likely.

"At the higher level — in other words, where people are watching it — there is very little incentive to breach integrity and therefore it is unlikely that it will happen," he said.

"Our conclusion, based on all of the evidence," Lewis said, "is that match-fixing is unlikely at the level of the Grand Slams."

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