Police are investigating a complaint of extortion against the woman at the centre of the sex scandal involving Australian leg-spinner Shane Warne.

A private investigator hired by the complainant, Gavin Varejes who is an associate of Warne's in Johannesburg, said he expected the woman, Helen Cohen Alon, to be charged.

"We've laid a complaint with the police and they are investigating it," Warren Goldblatt told Reuters from Johannesburg on Sunday.

"We believe a prima facie case exists and that a charge of extortion will be laid against Cohen Alon in the near future."

The Sunday Times in South Africa reported that police questioned Cohen Alon on Thursday after Varejes laid the complaint.

SUGGESTIVE MESSAGES

Cohen Alon, 45, alleges she and Warne had an affair last year and that the Australian cricketer bombarded her with suggestive messages for more than a year after their relationship ended.

Cohen Alon said Varejes offered her 200,000 rand ($27,280) to stay silent about her alleged fling with Warne after she threatened to sell her story, but that Varejes paid her only 100,000 rand.

Her lawyer told the Sunday Times that Cohen Alon planned to lay complaints of crimen injuria (criminal injury), defamation and defeating the ends of justice against Varejes.

In a separate interview with Reuters Television on Saturday, Cohen Alon said: "Charges have been made at the police station. I can't go into that because it is a sensitive issue.

"I have challenged Mr Shane Warne and Gavin Varejes and everybody who's trying to defame my name at the moment to go on lie detector tests.

"What I've also asked is for a media conference in Australia because the Australian media really tried to assassinate my character quite badly and I'm there to take all of them on as a woman alone."

Warne is serving a year's ban from the game after testing positive for a banned diuretic.

He is the second-highest wicket-taker in Test cricket with 491 from 107 matches. Warne toured South Africa with the Australia team in February-March 2002.