Two women standing as Green party candidates in the local elections have been arrested over alleged antisemitic social media posts.

The women, running in seats for Lambeth council, south London, were arrested by the Metropolitan police on Thursday morning.

The Green party declined to comment, citing the ongoing police inquiry, but the women are understood to be Saiqa Ali, a Lambeth Green candidate for Streatham St Leonard’s ward, and Sabine Mairey, who was standing in Lambeth’s Clapham Town.

The Met said in a statement: “Police have arrested two women, aged 57 and 54, on suspicion of stirring up racial hatred online, an offence under section 19 of the Public Order Act 1986. They remain in police custody.

“The arrests follow an investigation launched after concerns were reported to police on Tuesday 21 April about antisemitic material that had been posted online.”

Ali’s Instagram account is set to private but screenshots indicated she had posted an image of an armed man wearing a headband of the banned Islamist group Hamas along with the slogan: “Resistance is freedom”.

Another screenshot indicated that Mairey had shared a post which included the text: “Ramming a synagogue isn’t antisemitism. It’s revenge.”

A Lambeth council “notice of poll” document recorded that Ali had a home address in Croydon and had been nominated to stand as a Green party candidate.

Mention of her as a candidate has been removed from Lambeth Greens’ website, but archived records of the page described her as a community leader and Southern Women’s Aid Network founder.

Earlier this month she issued an apology “for any offence or distress caused to anyone by my social media posts” after the Lambeth Labour group accused her of sharing antisemitic posts that “repeat harmful tropes about Jewish people”.

There was also no mention of Mairey on the Lambeth Greens’ website.

A notice of poll recorded her as having an address in Lambeth, where she has been closely involved in activism to save an estate marked for demolition.

Lambeth council, a longtime Labour stronghold, is one of the Greens’ top targets in London and the party has been projected to make gains.

It currently has four councillors but a recent multilevel regression and poststratification (MRP) poll, based on a survey of 2,022 Londoners conducted by JL Partners, indicated the party could take as much as 34% of the vote and emerge as the second-biggest political force in the inner London borough.