Actor and AIDS activist Richard Gere brought thousands of sex workers to their feet on Wednesday, urging them to insist their clients use condoms.

"No condoms, no sex!" Gere shouted at an AIDS awareness event in Mumbai, the country's financial and entertainment hub.

He urged the crowd of more than 15,000 people to repeat the chant after him.

Gere and Indian actress Bipasha Basu presented awards to those spearheading HIV prevention campaigns.

Earlier, Gere met sex workers who explained how they use pictures and books to persuade fellow prostitutes to insist on safe sex. But they said it was difficult getting regular customers to use condoms.

Gere launched the "Heroes Project" four years ago to spread the message of prevention to Indians.

India, with 5.7 million infections, has the world's largest number of people living with HIV and AIDS. Campaigns aimed at prostitutes and truck drivers — both high-risk groups — have helped increase knowledge about the disease.

"Before, there was a total lack of knowledge among sex workers about HIV and even about their own bodies," Gere told The Associated Press. "Now there is a radical change."

Aid workers estimate Mumbai has 10,000 sex workers.

Vijaymala Dopukwar, a sex worker-turned-aid worker, said she had resisted going for medical checkups until a few years ago.

"The social worker would keep telling me to get checked up, but I was not ill so I refused to go," she said. "I didn't even know what a condom was, let alone how to use it."

Now she insists sex workers turn away customers who don't use protection, even if they offer to pay more money.