LGBT activist Carl Katter, half-brother of the anti-gay politician Bob Katter, has called on his resident city Melbourne to cut its ties with St Petersburg over its “homosexual propaganda” laws.

Carl Katter has started a campaign urging Melbourne City Council to break off it sister relationship with St Petersburg over laws banning the “promotion” of gay and trans identities to minors, enacted by the Russian city in February of last year.

Venice and Milan have already cut their sister ties with St Petersburg over the laws.

“It is referred to as the gay propaganda law, but it is all-encompassing,” said Carl Katter.

“Melbourne is one of the most progressive cities of the world and one of the greatest cities of the world and our mayor and council should be proud of that and stand up to such blatant homophobia.”

A spokesperson for the City council said: “The City of Melbourne is concerned about this legislation and understands that the Australian government has made representations on this matter.”

Carl Katter’s Change.org petition to break off Melbourne’s ties with St Petersburg has gathered almost 6,000 signatures.

He publicly came out as gay in 2011 in response to his half-brother’s comments at a Christian anti-equal marriage rally, at which he said same-sex marriages were “a joke”.

He also slammed Bob Katter’s 2012 anti-equal marriage campaign video in which he promised to “stand up to the Greens and other minority groups.”

Bob Katter, an outspoken opponent of equal marriage, founded Katter’s Australia Party (KAP) in 2011.

Recently a member of the party who was suspended for tweeting that he thought gay people should not allowed to be teachers said that equal marriage was making KAP “collapse”. He was the second party member in a matter of days to be forced to leave over homophobic comments.

Bob Katter himself was forced to step in last month when a pro-equal marriage candidate, Steven Bailey was asked to quit the party over his pro-equality stance.