US SUPREME court justice Ruth Bader Ginsburg, a towering women's rights champion who became the court's second female justice, has died aged 87 at her home in Washington.

A statement from the court said Ginsburg died as a result of complications from metastatic pancreatic cancer.

Following the announcement huge crowds formed outside the Supreme Court of those remembering her.

Her death just over six weeks before US election day is likely to trigger a fierce battle over whether President Donald Trump should nominate her replacement at the highest court in America, or if the seat should remain vacant until the result of the race in November against Democratic challenger Joe Biden is known.

The US senate majority leader Mitch McConnell said senators will vote on Trump's choice to replace Ginsburg, even though it is an election year.

Trump called Ginsburg an "amazing woman" and did not mention filling her vacant supreme court seat when he spoke to reporters following a rally in Minnesota.

Biden said the winner of the November election should choose Ginsburg's replacement.

"There is no doubt - let me be clear - that the voters should pick the president and the president should pick the justice for the senate to consider," Biden told reporters in Delaware.

Former president Barack Obama was among those paying tribute to Ginsburg.

He said: "Over a long career on both sides of the bench - as a relentless litigator and an incisive jurist - justice Ginsburg helped us see that discrimination on the basis of sex isn't about an abstract ideal of equality; that it doesn't only harm women; that it has real consequences for all of us. It's about who we are - and who we can be."

Ginsburg announced in July that she was undergoing chemotherapy treatment for lesions on her liver, the latest of several battles with cancer.

She spent her final years on the bench as the unquestioned leader of the court's liberal wing and became something of a rock star to her admirers.

Young women especially embraced the court's Jewish grandmother, affectionately calling her the Notorious RBG, for her defence of the rights of women and minorities, and the strength and resilience she displayed in the face of personal loss and health crises.

Those health issues included five bouts with cancer beginning in 1999, falls that resulted in broken ribs, the insertion of a stent to clear a blocked artery and assorted other hospital treatments after she turned 75.

She resisted calls by liberals to retire during Obama's presidency at a time when Democrats held the senate and a replacement with similar views could have been confirmed.

Instead, Trump will almost certainly try to push Ginsburg's successor through the Republican-controlled senate - and move the conservative court even more to the right.

Ginsburg antagonised Trump during the 2016 presidential campaign in a series of media interviews, calling him a faker. She later apologised.

Her appointment by then-president Bill Clinton in 1993 was the first by a Democrat in 26 years. She initially found a comfortable ideological home somewhere left of centre on a conservative court dominated by Republican appointments. Her liberal voice grew stronger the longer she served.

Ginsburg, a mother of two, argued six key cases before the court in the 1970s when she was an architect of the women's rights movement. She won five.

At the time of her appointment, Clinton said: "Ruth Bader Ginsburg does not need a seat on the supreme court to earn her place in the American history books. She has already done that."

Following her death, Clinton said: "Her 27 years on the court exceeded even my highest expectations when I appointed her."

On the court, her most significant majority opinions were the 1996 ruling that ordered the Virginia Military Institute to accept women or give up its state funding, and the 2015 decision that upheld independent commissions some states use to draw congressional districts.

Besides civil rights, Ginsburg took an interest in capital punishment, voting repeatedly to limit its use. During her tenure, the court declared it unconstitutional for states to execute the intellectually disabled and killers younger than 18.