Pope Benedict praised the Australian Government on Thursday for apologising for past injustices to Aborigines, saying it was a courageous move to repair race relations and offered hope to the rest of the world.

Aboriginal dancers with painted faces and dressed in animal fur swept the ground with gum leaves in a welcoming ceremony as the Pope boarded a boat to cross Sydney Harbour to greet more than 100,000 Catholic pilgrims at World Youth Day.

One woman aboriginal dancer knelt in front of the 81-year-old pontiff, handing him a branch of gum leaves, which he waved in the air as he boarded the ship to lead 13 boats up the harbour.

The Pope said the ancient heritage of Aborigines, who have been in Australia for some 40,000 years, formed "an essential part of the cultural landscape of modern Australia".

"Thanks to the Australian Government's courageous decision to acknowledge the injustices committed against the indigenous peoples in the past, concrete steps are now being taken to achieve reconciliation based on mutual respect," said the pontiff in a welcoming speech with Prime Minister Kevin Rudd.

"This example of reconciliation offers hope to peoples all over the world who long to see their rights affirmed and their contribution to society acknowledged and promoted."

Rudd officially apologised to Aborigines in February.

Australia's 460,000 Aborigines make up about 2 per cent of the country's 21 million population and have consistently higher rates of unemployment, substance abuse and domestic violence, as well as a life expectancy 17 years less than other Australians.

ENVIRONMENT

The Pope also highlighted Australia's moves to combat climate change, with the government planning a carbon trading system aimed at cutting greenhouse gases by 60 per cent of 2000 levels by 2050, and called on "responsible stewardship" of the earth.

"It is appropriate to reflect upon the kind of world we are handing on to future generations," said the Pope before his first appearance at World Youth Day celebrations, which are being held from July 15-20.

"I note that Australia is making a serious commitment to address its responsibility to care for the natural environment."

Australia, one of the world's highest per capita greenhouse emitters due to coal-fired power stations, is in the grip of the worst drought in 100 years and is struggling to save its major river system that feeds the nation's food belt.

Australia plans to introduce a carbon trading system by 2010.

The Catholic Church hopes World Youth Day, the brainchild of the late Pope John Paul II, will revitalise the world's young Catholics at a time when the cult of the individual and consumerism have become big distractions in their daily lives.

Sexual abuse in the Catholic Church has overshadowed the Pope's visit, with the Church reopening a 25-year-old abuse case in Australia only days before the pontiff arrived.

The Pope has said he will apologise to Australian victims of sexual abuse in the Church. Broken Rites, which represents abuse victims, has a list of 107 convictions for Church abuse, but says there may be thousands more victims as only a few go to court.

The Pope confronted the issue of sexual abuse in the Church during a visit to Washington in April, meeting victims and vowing to keep paedophiles out of the priesthood.

Some sex abuse victims plan to protest against the papal visit in Sydney, along with a group called "No Pope" which opposes church teachings on sex and marriage.