LONDON - Tennis faces "very significant" integrity problems, particularly at the lower levels of the sport, caused by the sharp increase in internet betting, an independent report concluded in its interim finding on Wednesday.

The Interim Report of the Independent Review of Integrity said that its two-year investigation had not revealed widespread corruption at the highest levels of the professional game globally although "there is nonetheless evidence of some issues at these levels".

Among its recommendations are a review of appearance fees and the ranking system and a halt to the sale of sporting data by the International Tennis Federation (ITF) at the low-level Futures events.

It also recommended greater monitoring of the lower levels where one investigator said there were a "tsunami" of problems.

The Review was commissioned by tennis' major bodies (ATP, WTA, ITF and Grand Slam Board) in 2016 following a report by the BBC and BuzzFeed News which claimed 16 players ranked in the world's top 50 had been flagged to the Tennis Integrity Unit (TIU) over suspicions that matches had been thrown.

The panel said: "the integrity problems are greatest where prize money relative to costs, prospects of advancement, pubic interest and attention, and financial resources of tournaments are lowest".

It also said the advent of online betting and the sale of official live scoring date have greatly exacerbated the problem and recommends that the ITF ends its date sale agreement at Futures events.

It added that there are no simple solutions but called on the sport "to address and limit the betting markets that ultimately drive, and give expression to, the problem; and to improve the systems of preventing and disrupting breaches of integrity, and for detecting and sanctioning them when they occur."

The report paints a picture of financial privation among many of the sport's 15,000 professionals, with many at the lowest level struggling to cover the costs of competing. This, the report said, made betting on matches more attractive to players, many of whom admitted knowledge of match-fixing.

A survey of 3,200 players found that 16 percent indicated they had first-hand knowledge of players betting on matches, 11 percent knew of inside information being provided and 14.5 percent of match-fixing. Of these, 35 percent said they had knowledge of more than one instance.

Tennis' governing bodies have committed to implementing the report's final findings after a period of consultation.

The panel, which was chaired by Adam Lewis QC, took statements from 200 key stakeholders, conducted more than 100 interviews and collected more than 3,200 survey responses.

(Reporting by Neil Robinson Editing by Christian Radnedge) ((neil.robinson@thomsonreuters.com;))