OTTAWA (AFP) - A few thousand anti-abortion demonstrators held an annual rally in front of Canada's Parliament on Thursday (May 12), as the deeply polarising rights issue flares up in the United States.

They waved placards that read "Pray to end abortion", egged on by organisers on megaphones who were often drowned out by a smaller counter protest group of mostly young women chanting: "Our body, our choice."

Emily Helferty, 23, told AFP she hopes a leaked draft opinion that showed the US Supreme Court's conservative majority preparing to overturn Roe v. Wade, the case enshrining abortion rights in America, will mark "a turning point" in the debate in favour of a ban.

"I think that would be great. I mean, a lot of people have been praying for this for a really long time," she said, flanked by her parents.

The landmark 1973 ruling guaranteed abortion access across the United States. In Canada, a 1988 top court ruling struck down restrictions on abortions.

Thirty-one-year-old deacon Marc Gaudet was also optimistic, saying: "I'm really prayerful and hopeful that this will rekindle a renewed sense of the dignity of all life."

But rally organiser Jack Fonseca was more guarded, telling a news conference a day earlier it would take "many years" to bring in a ban on abortions in Canada.

"We first have to get a majority of pro-life MPs in Parliament, and that still won't be enough," he said, noting that 80 per cent of Canadians are in favour of abortion rights.

At the rally, several protesters in favour of abortion rights wore red dresses like characters from the dystopian television series The Handmaid's Tale, about a totalitarian society that subjects fertile women to child-bearing slavery. It was based on Canadian author Margaret Atwood's 1985 novel.

A man waved a placard that said: "Let's make Margaret Atwood fiction again." Others read: "Abortion is health care" and "Reproductive rights are human rights".

At a news conference, Prime Minister Justin Trudeau evoked the concerns of the group in favour of abortion rights, saying women around the world are "very worried that there is going to be a rolling back of significant gains that they have made, that we have all made, in women's rights".

His liberal government has pledged to defend those rights, and possibly codify access to abortions in Canada.