Thirteen players were sanctioned in 2017 after investigations by the Tennis Integrity Unit (TIU).

Five were banned over match-fixing claims, while other cases involved low-ranked players betting on tennis.

The number of match alerts for suspicious betting patterns fell last year to 241, from 292 in 2016.

The alerts do not necessarily indicate wrongdoing but are seen as an indication that corrupt activity may have occurred.

Nine players and officials were banned in 2016. No officials were banned last year.

“There is no doubt that most players and officials conduct themselves in an exemplary fashion, but the small minority who choose to break the rules are a continuing concern,” TIU director Nigel Willerton said in its annual report.

• Read the full report

The TIU said a wider interim report on corruption in tennis is due in early 2018.

It follows a report by the BBC and BuzzFeed News two years ago which claimed 16 players ranked in the world’s top 50 had been repeatedly flagged to the unit over suspicions they have thrown matches in the past decade.

Since then the budget for the TIU, set up in 2008 and funded by the sport’s governing bodies and the four Grand Slams, has been increased with $3.71m (£2,75m) being set aside for 2018.

The number of full-time staff has risen to 17 from just a handful three years ago, while a training and education unit will be established this year to help educate young players against the risks of corruption.

Player sanctions in 2017

(Career-high ranking in brackets)

Match-fixing

Alexandru-Daniel Carpen, Romanian (1,088, singles) – Lifetime ban

Konstantinos Mikos, Greek (933, singles) – Lifetime ban

Junn Mitsuhashi, Japanese (295, singles) – Lifetime ban, $50,000 fine

Nikita Kryvonos, American (389, singles) – 10-year ban, $20,000 fine

Nick Lindahl, Australian (187, singles) – Seven-year ban, $35,000 fine

Betting

Calum Puttergill, Australian (1,148, singles) – Six-month ban, $10,000 fine

Mihaita Damian, Romanian (1,439, doubles) – 12-month ban, $5,000 fine

Marius Frosa, Romanian (1,920, singles) – Eight-month ban (four months suspended), $1,000 fine

Samuel Ribeiro Navarette, Spanish (723, singles) – Eight-month ban (four months suspended), $1,000 fine

Other

Brandon Walkin, Australian (980, singles) – Passed a corrupt proposal to third party: six-month ban, suspended for six months

Piotr Gadomski, Polish (338, singles) – Breached original suspension by attending professional tennis event: 18-month suspension added to existing seven-year ban (suspended pending no further breaches)

Isaac Frost, Australian (458, singles) – Provisional suspension pending TIU investigation

Oliver Anderson, Australian (639, singles) – Provisional suspension pending TIU investigation