SAO PAULO (AFP) - Hundreds of thousands of marchers turned out Sunday (May 29) for Sao Paulo's 20th annual Gay Pride parade, one of the biggest such events anywhere in the world, organisers said.

Participants said one goal of this year's procession is to offer a major show of support of proposed federal legislation that would allow Brazilians to claim the gender identity of their choosing, "which may or may not correspond to their gender at birth," the text of the bill states.

The legislation, if approved, would also require government health providers to pay for sex-change operations.

Representatives of the LGBT (Lesbian, Gay, Bisexual and Transgender) community began gathering at 10 am local time (1300 GMT) on the Avenida Paulista ahead of the start of the hours-long procession.

More than 1,000 police were expected at the parade, which also planned to include protests against acting president Michel Temer, who is replacing Dilma Rousseff while the Senate proceeds with her impeachment trial.

The city's first Gay Pride march drew a mere 2,000 people in 1996. But it has become a top tourist draw in this city of 20 million, second only after the Formula One car race.

One LGBT rights activist, Viviany Beleboni, 27, told reporters she would march with a Bible in hand to protest an evangelical group in parliament that has blocked pro-LGBT legislation.

A draft law to punish homophobic actions has been stalled for years by Catholic and evangelical blocs. Brazil's Supreme Court in 2011 recognised the stable unions of homosexual couples, guaranteeing them the same rights as enjoyed by heterosexual couples.