More than two dozen top tennis players should be investigated for possible links to betting rings, according to an Italian prosecutor.

Roberto di Martino says their names have appeared in evidence seized from gamblers suspected of fixing matches.

They include two players who have been ranked in the world's top 20.

So far, only Potito Starace and Daniele Bracciali, two Italians, have been investigated and charged but Di Martino says others should be investigated.

He also told the BBC's File on 4 programme and BuzzFeed News that tennis authorities should be doing more with the evidence he has gathered.

"Surely if these foreign players were Italian, they would certainly have been at least questioned," Di Martino said. "They should have provided some explanations."

Listen to Simon Cox's report for File on 4 at 20:00 GMT on Tuesday on Radio 4, or catch up on the BBC iPlayer

Di Martino has been conducting a two-year inquiry into a suspected match-fixing ring involving Italian tennis players and gamblers.

His inquiry has obtained internet chat logs and recordings of phone calls between players and gamblers.

He says more than two dozen non-Italian players are mentioned by the gamblers and believes these players should be investigated by the Tennis Integrity Unit (TIU).

He would not reveal the identity of the players mentioned in the seized evidence but he added: "Interestingly, they are not so-called second-tier tennis players, but also players of some importance."

Starace and Bracciali have been accused of conspiring to fix matches between 2007 and 2011 for up to 50,000 euros (£38,800).

They are due to appear in court in May and deny charges of conspiracy to commit sports fraud.

Di Martino claims he has "concrete evidence" about two specific matches in 2009 and 2011 in Barcelona involving Starace.

He suspects there are 30 other matches that may have been corrupted, by a number of players, including at Wimbledon and the French Open.

The BBC and BuzzFeed News have learned the names of the players contained in Di Martino's investigation files.

A source close to the inquiry said two of these players had been described in an internet chat log between two gamblers as their "horses".

The source told us using this term could mean the players were under the control of the gamblers.

These chat logs were among hundreds of files prosecutors sent to the TIU three months ago.

But Di Martino said TIU investigators had visited him and made it clear they were "exclusively" interested in the Italian players.

"The international aspect seems more problematic than a situation involving a few Italian players," he said.

"It would be possible to identify, possibly hit, many foreign players who definitely are part of this system."

Di Martino criticised the TIU for failing to act on hundreds of alerts it has received about suspicious betting on tennis matches.

"I do not understand why there was no real initiative by the integrity unit to establish if there was something dirty behind this," he said.

Tennis has been accused of covering up evidence about widespread gambling on matches by players.

In January, tennis authorities launched an inquiry into corruption after the BBC and Buzzfeed News revealed the TIU had failed to act on repeated warnings about 16 top players suspected of being involved in throwing matches.

The TIU said in a statement that it "acts on all evidence" as part of its "a long-standing and total commitment to eradicating betting-related corruption in the sport".

It said it was investigating the allegations against Bracciali and Starace.

Courtesy BBC