Thousands rally across Australia in support of Indigenous reform

Thousands of people have rallied in Australia to back a campaign to recognise the country's Indigenous people in the constitution ahead of a referendum later this year, after a recent dip in support for the change.

On Sunday, an Australian Council of Social Service tweet showed Sydney rally attendees in T-shirts with the words "Vote Yes" and caps with the words "The Uluru Statement", referring to a key document that calls for an Indigenous Voice.

Yes23, the group behind more than 25 rallies nationwide, told the Reuters news agency the crowd in Sydney was around 3,000 and that it expected up to 25,000 people to participate in total.

"These community events are opportunities for people to come together and gain valuable information about the importance of a successful referendum later this year," Yes23 campaign director Dean Parkin said in a statement.

The referendum, likely to be held between October and December, seeks to amend the constitution and establish an advisory body – the Indigenous Voice to Parliament – to give Aboriginal and Torres Strait Islander people a direct say in policies that impact them.

Prime Minister Anthony Albanese's centre-left Labour government backs the change, while the opposition Liberal-National conservatives urge a "No" vote.

The day of action comes after support for the referendum appeared to be ebbing according to a poll last month, which showed "No" ahead for the first time, 51 percent to 49 percent.

Opponents, including some Indigenous people, have said the proposal lacks detail and will divide Australians.

"We do not really focus on the polls, what we focus on is the work that is involved in getting out and talking to people," Yes23 director Rachel Perkins told ABC television on Sunday.

Indigenous Australians, who account for 3.8 percent of the population, face disadvantages, including discrimination, poor health and education outcomes and high incarceration rates.