The former mistress of the late Australian billionaire Richard Pratt claimed on Monday that her lover asked her to continue her relationship with his bodyguard even if the former military man was abusive.

Madison Ashton, who sued Mr Pratt's estate for about $10 million, recalled that she started to have a sexual relationship with the billionaire from 1995 to 1996. In 2003, she agreed to be his full-time mistress in exchange for $500,000 annual allowance and a Mercedes-Benz that costs $150,000.

That was on top of $36,000 for rent and $30,000 for travel due monthly.

She claimed that Mr Pratt likewise offered to establish a $2.5 million trust fund for each of her two children. However, Ms Ashton told the New South Wales Supreme Court that the cardboard businessman reneged on the agreement and only gave her a fraction of the amount.

She got the regular payments from December 2003 to February 2005, but the encounters with Mr Pratt became less often in April 2004 when another of the billionaire's mistress - Shari Lea Hitchcock who introduced them - returned

Ms Ashton also disclosed that Mr Pratt urged her to continue having sexual relationship with his bodyguard, Sean Bowman, who was a former member of the New Zealand Special Forces and an ex-assassin. Toward the end of her relationship with Mr Bowman, he became abusive, the woman's lawyer told the court.

Ms Ashton explained that Mr Pratt encouraged her to maintain relationship with the abusive bodyguard because he was likely blackmailing the billionaire who probably had some damaging information about his employer.

"Therefore you can best serve me by serving him," Ms Ashton quoted Mr Pratt.

The hearing of the case continues.