An anti-abortion event in South Australia has had to change location at the last minute because of "violent threats", according to South Australia's Liberal Opposition Leader.

Politicians from the Liberal Party, Labor, Family First and SA Best were due to speak at the Enid Lyons List training day today.

The event has the aim of encouraging young people to "fight for the human rights of the unborn" and was due to be held just five days before the state's laws decriminalising abortion come into effect and on the same day as a state by-election.

More than a dozen police officers attended the Thebarton Community Centre in Adelaide's west to ensure the group's members could safely attend the event.

A small group of pro-choice protesters gathered outside but no one from the organisation showed up.

Neither police at the scene nor the venue management was told Enid Lyons List would not be attending.

Opposition Leader David Speirs said the event had been moved and he would still attend at its new, undisclosed location.

"I think it has been very unfair how this has been politicised," he said.

"I want to be involved in a progressive agenda for this state that casts an alternative vision for this state.

"A hundred young women are attending this event — young women who want to be involved in the leadership of this state — but because of violent threats against those young women, that event has had to be moved, that event has needed police protection, that event has needed to have security and that is because of the hate perpetuated against those young women.

"How disappointing is that."

On Thursday, South Australia will become the last state in the country to decriminalise abortion, 16 months after the reforms were passed by state parliament.

Mr Speirs said he supported the decimalisation of abortion but had concerns about late-term abortion and was "quite within my rights" to have that view.

'Community outrage' forced move

Pro-choice advocate Ana Obradovic, who protested outside the Thebarton Community Centre and also organised the protest in the Adelaide CBD last night, said it was a "win" that "community outrage" had forced the event to move.

"These people have been feeling very confident with the overturning of Roe v Wade in the United States," she said.

"I think it's really important that these people don't go unopposed, they should feel like the minority that they are in society.

"We should be saying for whatever reason, at whatever, women and trans people have the right to choose how many people they do or do not have using whatever medical technology is available."

Journalist 'perpetuating hatred'

Jack Batty is running for the Liberal Party in a by-election today to replace former deputy premier Vickie Chapman, who championed the abortion bill.

When asked about the training day at a media conference about the by-election, Mr Speirs lashed out at a female ABC journalist for asking Mr Batty whether he supported the event.

Mr Speirs said the journalist was "perpetuating hatred" and "violence" towards young women for asking about the Enid Lyons List event.

"This is a leadership workshop for young women," he told reporters.

"To characterise them having a particular view as a protest is perpetuating hatred … and threats of violence against young women in this state.

"For a journalist to abrogate all forms of responsibility to do that is so disappointing.

"This event as far as I know isn't to do with abortion; the Enid Lyons List has a particular framework of values, one of which I understand to be pro-life."

On its website, Enid Lyons List said it sought "to prepare and equip women leaders to take office in places of influence" and "to support the elevation of women who advocate for the protection of human life".

ABC News tried to contact an organiser of the Enid Lyons List event and was told no one from the organisation would be speaking to the media today.