PRETORIA, South Africa - South Africa will treat all HIV-positive babies and expand testing, the president announced Tuesday on World AIDS Day in a dramatic and eagerly awaited shift in a country that has more people living with HIV than any other.

President Jacob Zuma's speech Tuesday was viewed as a definitive turning point for a nation with a legacy of leaders who rejected treatment based on medical science and delayed lifesaving measures.

Zuma compared the fight against AIDS to the decades-long struggle against the apartheid government, which ended in 1994 with the election of Nelson Mandela in the country's first multi-racial elections.

"At another moment in our history, in another context, the liberation movement observed that the time comes in the life of any nation when there remain only two choices: submit or fight," Zuma said. "That time has now come in our struggle to overcome AIDS. Let us declare now, as we declared then, that we shall not submit."

Zuma, credited with already making important policy changes on AIDS, was greeted with a standing ovation when he entered a Pretoria exhibition hall filled with several thousand people, many of them AIDS activists, medical professionals, or both.

UNAIDS executive director Michel Sidibe, who took the podium shortly before Zuma, told the president: "What you do from this day forward will write, or rewrite, the story of AIDS across Africa."

On Tuesday, in response to a plea from Zuma, the United States announced it was giving South Africa $120 million over the next two years for AIDS treatment drugs.

In his speech, broadcast across South Africa on state radio and television, Zuma said new policy changes would take effect in April.

"It means that people will live longer and more fulfilling lives," he said.

The new steps included treatment for all HIV-positive children under 1 year old, and earlier treatment for patients infected with both the virus that causes AIDS and tuberculosis and for women who are pregnant and HIV-positive.

He said all health institutions, not just specialist centres, would provide counselling, testing and treatment.

Zuma also called on South Africans to be tested for HIV. But, contrary to speculation in recent days, he did not take an AIDS test Tuesday.

"I have taken HIV tests before and I know my status," he said. "I will do another test soon as part of this new campaign. I urge you to start planning for your own tests."

After listening to his president, advertising consultant Tedson Tibani said the steps Zuma outlined could significantly reduce infections within a few years. Tibani said putting more people on drugs would cost money, but said he was hopeful others would follow the U.S. in donating money.

"There's a kind of hope the president has instilled," Tibani said. "I'm very happy with that. We've never had that before."

Setjhaba Ranthako brought his 4-year-old daughter Tshegofatso to hear Zuma's speech, saying education should start early.

"I've see in President Zuma a person who's willing to listen, and say, 'Here I am, come with your views, and let's turn your views into an effective campaign to combat the spread" of AIDS, said Ranthako, who works with a group that raises awareness about AIDS among men.

In some ways, Zuma is an unlikely AIDS hero. In 2006, while being tried on charges of raping an HIV-positive family friend, he was ridiculed for testifying that he took a shower after sex to lower the risk of AIDS. He was acquitted of rape.

Zuma, a one-time chairman of the country's national AIDS council, may never live down the shower comment. But he has won praise for appointing Dr. Aaron Motsoaledi as his health minister. AIDS activists say Motsoaledi trusts science and is willing to learn from past mistakes.

South Africa, a nation of about 50 million, has an estimated 5.7 million people infected with HIV, the virus that causes AIDS - more than any other country in the world.

The health minister under Zuma's predecessor distrusted drugs developed to keep AIDS patients alive, instead promoting garlic treatments. Zuma's government has set a target of getting 80 per cent of those who need AIDS drugs on them by 2011.

A Harvard study of the years under President Thabo Mbeki, who questioned the link between HIV and AIDS, concluded that more than 300,000 premature deaths in South Africa could have been prevented had officials here acted sooner to provide drug treatments to AIDS patients and to prevent pregnant women with HIV from passing the virus to their children.

After Zuma won a power struggle within the governing African National Congress, the party forced Mbeki to step down late last year after almost a decade as president. Zuma took over after elections in April.

The crowd that had greeted Zuma like a rock star before his speech rose to their feet when Zuma finished Tuesday. Then he danced along with a choir that sang: "Zuma, you are blessed."