Former Labor prime minister Paul Keating has turned his caustic wit on the Greens, labelling the party “a bunch of opportunists and Trots”.

Keating, who was prime minister between 1991 and 1996, told a Labor party rally in Sydney the Greens were aiding conservatives by reducing Labor’s ability to form government.

It was his first public appearance of the 2016 election campaign.

“They’re a protest party, not a party of government, but their game is to nobble the party of government that can actually make changes,” Keating said.

“You can’t be a government when you’ve got a bunch tearing away at you, trying to pinch a seat here and there, all to make themselves look important.”

Keating addressed the rally in aid of Labor shadow cabinet member Anthony Albanese, who is under pressure in his inner-western Sydney seat of Grayndler.

The seat has come under sustained Greens attack after electoral commission redistributions cut the traditional working-class stronghold of Marrickville, as well as Albanese’s home and office, from the electorate.

Keating castigated the Greens for positioning themselves as the true Australian progressive party, saying it was Labor who introduced legislation to protect the Daintree, Jarvis Bay and Antarctica.

The Greens had also failed environmentalists by blocking an emissions trading scheme in 2009, he said.

“They purloined the name Greens. We’re more green than they are,” he said.

“Ratting on Rudd with the ETS scheme and walking away from the Malaysia solution, things that required a bit of courage ... they could’ve been the yellows.”

Keating said the Labor party would always eschew ideology for “what works”.

He said easing monetary policy could no longer spur business investment, and governments now had to intervene with infrastructure spending to kickstart economies around the world.

Governments could no longer look to the market for fixing everything, he added: “Governments have tucked themselves away and let central banks lower interest rates in the hope, like lighting a match, if you strike it enough there might be a flame.”

“The model has to change. That means a bigger role for government in things like infrastructure (and) the provision of important public services.”