According to the court file, the plaintiff, Ian Baum, 59, believes that Thomas "did not take the necessary precautions" to avoid contamination.
"He hid the fact that he had HIV and passed it on to me," he said in an interview with The Times.
According to court documents, Baum says he found out about Thomas' HIV status by researching pills the former player was taking on the internet, claiming they were vitamins when they were actually a treatment for HIV.
The plaintiff, who claims he was HIV-negative when he started dating Thomas in 2013, also says Thomas was "coercive and overbearing" to keep his HIV status from coming out publicly.
The former three-quarter revealed he had HIV in 2019.
Gareth Thomas, 48, 100 caps with Wales, was the first rugby player in history to come out as gay in 2009. Since retiring from the field, he has become an activist for gay rights.
© 2022 AFP