South Africans have expressed widespread support for the double Olympic champion Caster Semenya, who will run her last 800m on Friday before the imposition of controversial new rules limiting testosterone in female athletes.

Tokozile Xasa, the sports minister, said on Thursday that the South African government was disappointed with the ruling by the court of arbitration for sport that women with unusually high testosterone levels, such as Semenya, would have to take medication to significantly reduce their testosterone before they were permitted to compete internationally at distances between 400m and a mile.

“As the South African government we have always maintained that these regulations trample on the human rights and dignity of Caster Semenya and other women athletes,” she said.

The African National Congress, the ruling party, issued a statement describing the judgment as “disheartening” and accused the International Association of Athletics Federations (IAAF) of “acting in a prejudicial manner that divides rather than unites athletes”.

The new rules oblige “hyperandrogenic” athletes – those with “differences of sexual development” (DSD) – to lower their testosterone levels if they wish to compete as women.

Under the rules to take effect on 8 May, female athletes with high natural levels of testosterone wishing to compete in events from 400m to a mile must medically limit that level to less than 5 nanomoles per litre (nmol/L). The normal level for women is below 2 nmol/L.

The bitter controversy over Semenya has been followed closely in her home country, where many have seen the ruling in a broader global political or historical context.

“The decision will have far-reaching implications, not just on Caster Semenya, but it will also apply to transgender and intersex people,” said Letlhogonolo Mokgoroane, a police development and advocacy fellow at Sonke Gender Justice, a South African NGO. “But I’m not surprised the IAAF’s rules have been used to target women from the global south.”

Semenya, 28, grew up in a village in the poverty-hit province of Limpopo and studied sports sciences at university. She began running as training for football before her talent was recognised but rapidly began winning medals at the highest level.

Seen as an inspirational hero in South Africa, she was picked to carry the country’s flag at the 2012 Olympics and won a silver medal in the competition, later upgraded to gold after a Russian athlete was disqualified for doping.

Athletics South Africa (ASA) is now considering approaching the Swiss federal tribunal in an effort to overturn the judgment. The national governing body for athletics said it was “deeply disappointed and profoundly shocked” and compared the decision to the repressive and racist apartheid system in South Africa that ended 25 years ago.

South African athletes have also rallied behind Semenya. Wayde van Niekerk, the men’s Olympic 400m gold medal holder, said the issue “goes beyond track and field”.

“Caster is fighting … for women in sports, in society, and I respect her for that,” he told local reporters.

The sprinter Anaso Jobodwana accused the IAAF of “a useless, degrading witch-hunt”.

Many ordinary South Africans also see Semenya as a victim of discrimination. “She’s a hero, but just because she’s a bit different from other people they are trying to take that away from her,” said Amelo Mthembu, a 44-year-old shopkeeper in west Johannesburg. “I think they feel threatened.”

Mthembu’s 21-year-old daughter, Angel, said Semenya should be celebrated. “Sport is about diversity, not making everybody conform. The whole point is that everyone can take part and be themselves,” she said.