The Tennis Integrity Unit said operators reported suspicious betting activity around 24 matches between April and June while most major competitions were suspended as a result of the novel coronavirus (Covid-19) pandemic.
In addition, a retroactive alert was also filed for one match from the 2019 World Tennis Association's WTA125k series.
In the same quarter of 2019, 33 suspicious matches were reported, meaning 2020's 24 reports represented a 27.3% decline.
TIU noted that the continued suspicious betting despite most events being suspended showed that match-fixing remains a serious issue in the sport.
“Suspicious betting on tennis during the lockdown is seen as a firm indicator that corruptors remain active, and are likely to increase their focus on the sport when professional tennis resumes in August,” it said.
During the quarter, the TIU also took disciplinary action against three players and two officials.
The players included 21-year-old Egyptian player Youssef Hossam, who received a lifetime ban after being found guilty of eight cases of match-fixing, six cases of facilitating gambling, two cases of soliciting other players not to use best efforts, three failures to report corrupt approaches and two failures to co-operate with a TIU investigation. Hossam had been ranked as high as 291 in the ATP World Rankings in 2017.
Tunisian player Majed Kilani, Brazilian player Pertti Vesantera, French official Anthony Pravettoni and Venezuelan match official Armando Alfonso Belardi Gonzalez all received suspensions and fines.
In addition, the TIU has launched a series of webinars for players, in order to educate them of enhanced integrity threats that may exist when the professional tours return.
The TIU has also been working closely with the president and executive team of the Egyptian Tennis Federation (ETF) to develop a bespoke integrity education strategy for Egyptian tennis.
In 2019, the unit received 138 reports over suspicious match activity in 2019, the lowest annual amount since its integrity data was first made public in 2015.