The furious mother of Olympic gold medallist Rhiannon Jeffrey has hit back at what she alleges is "age discrimination" against her daughter because of her relationship with a teenage swimming star.

Seventeen-year-old Aucklander Justin Wright went to court last week to fight for the right to continue swimming competitively after his parents withdrew their authorisation because of his relationship with 24-year-old Jeffrey.

The Herald on Sunday revealed the story of how he had effectively "divorced" his parents last week, sparking an international reaction.

The story ran everywhere from the Sydney Morning Herald in Australia, to the Daily Mail in Britain, to FOXSports, SwimmingWorldMagazine and USA Today in America.

Now, in an open letter to this paper, Jeffrey's Florida-based mother Anne Marie Jeffrey has angrily threatened to sue Wright's parents, Paul and Sandy Wright of Hobsonville in West Auckland, for age discrimination.

"I am Rhiannon Jeffrey's mother," she writes. "I raised her along with her sister Kirstie, just graduated from Duke University here in the US. I set very high standards for both my girls, and raising them alone in Florida was not easy."

Rhiannon "Rhi" Jeffrey won gold at the Athens Olympics in 2004, but has since moved to New Zealand in a bid to qualify for next year's London Games under her Kiwi coach David Wright (no relation).

But after she formed a romantic relationship with Justin, a talented young high school swimmer, his parents tried to break it up and bombarded West Auckland Aquatic Club members with emails, demanding their coach intervene.

Sandy and Paul Wright withdrew their consent for Justin to compete at Swimming NZ events, destroying his chances of qualifying for the World Cup in November - so he went to court last week and won, in what is believed to be a legal first.

Justin has moved out of his parents' home and into Rhiannon's Titirangi apartment.

He has acknowledged his relationship with his parents may be irreparably damaged, and Rhi said his parents had judged her without meeting her.

Now, Anne Marie Jeffrey has waded into battle.

"I am furious to say the least with the parents of Justin Wright," she writes. "I will take a stand.

"Please inform the Wright (now Wrong) family they should be supportive of their son, and swimming is not an extra curricular activity - it is a passion."