Former Olympic weightlifter Tracey Lambrechs says women are being told to "be quiet" when they complain about the fairness of transgender New Zealand weightlifter Laurel Hubbard competing in women's competitions.

Hubbard is on track to become the first transgender athlete to compete at an Olympics after the International Weightlifting Federation (IWF) modified the qualifying requirements for the Tokyo Games on Wednesday.

The 43-year-old still has to satisfy the New Zealand Olympic Committee's fitness and performance standards before being selected, but the prospect of her competing in Tokyo has already caused controversy.