Melbourne mother Allie was sent an invitation last weekend via the social networking website meetup.com to join an anti-vax playgroup with her one-year-old son.

The invitation from the the Outer Eastern Non-Vaccinated Toddler Playgroup was addressed to "Conscious Informed Parents", in what appeared to be an automatically generated email.

It reads: "I am starting this meetup in an attempt to connect with other Mums in the outer Eastern area of Melbourne that, like me, have done their research and chosen NOT to vaccinate their children and want to meet on a fortnightly basis to provide informal social interaction with other like-minded Mums & Dads with pre-school tots."

Created on March 7, the group appeared to have gained only five members by March 14.

The legitimacy of the group is not clear, and its organisers could not be immediately contacted via the website.

The group's page on meetup.com.

Allie, who requested that her last name not be published, said she was shocked to see the group on a mainstream website.

"Usually, these people stick to private Facebook groups," said Allie, whose son has received all the vaccinations for his age.

"This really is a community concern. I'm just terrified that we're going to end up with diseases that have been eradicated coming back, because people [don't] vaccinate their children."

Authorities have no power to stop anti-vaxxers and their unimmunised children gathering, but the playgroup plan is of concern to Health Minister Jill Hennessy.

"When it comes to vaccination the science is clear. It saves lives," she said.

"This sort of behaviour not only puts the health of their children at risk, it endangers the lives of other children in the community. I'd seriously encourage any parent to take advice from their GP before knowingly exposing their children to the risks of an anti-vax playgroup.

"Parents who may not have their own vaccinations up to date could also be a risk to unvaccinated children."

Some anti-vaxxers indicated they planned to set up childcare centres and playgroups for unimmunised children in response to "no jab, no play" policies in Victoria, NSW and Queensland that came into effect on January 1, 2016.

Under the laws, a child must be fully immunised for their age or on a vaccination catch-up program before enrolling at a childcare centre, kindergarten or family daycare centre. Children can be exempt only for medical reasons, but there is no exemption for "conscientious objection".

The laws, however, do not apply to unlicensed playgroups or parents' groups.

This week Prime Minister Malcolm Turnbull called on all other states and territories to introduce "no jab, no play" legislation, similar to Victoria's. The push could see unvaccinated children barred from childcare and preschool facilities across Australia.

Under Mr Turnbull's proposal, the immunisation rates of preschools and daycare centres would also be made public so parents would "know their children are safe when they drop them off".

The national vaccination rate is about 93 per cent and the government wants to push it to 95 per cent or higher.

An additional 200,000 children have been immunised since the government's "no jab, no pay" measure, which denies welfare payments to families with unvaccinated children, came into effect at the start of 2016.