The Labor leader only found out about the 20-strong group of members and senators through the media.

"That's what happens in Canberra. People go out and people chat about ideas. There is nothing unusual about this," he told reporters on Thursday.

"The Labor Party is united in our position that climate change is real, that we need to act on lowering our emissions.

"Good action on climate change means more jobs, lower emissions and lower energy prices."

The so-called Otis Group takes its name from the Canberra restaurant where the coal backers meet.

Labor deputy leader Richard Marles played down their secret meetings as a "total beat up".

"At the end of the day, people were having a dinner," he told Sky News.

"I don't think it's a big deal."

Shadow treasurer Jim Chalmers, from the party's right faction, also found out via the media.

"There's nothing unusual about colleagues catching up for dinner, and there's certainly nothing unusual about people getting together to talk about policy," Dr Chester said.

Scott Morrison poked fun at the breakaway group.

"I don't know if that's Milo and Otis (1980s movie) or it's just Otis or how many others there are involved in this," the prime minister told reporters.

"But more than 20 Labor MPs getting together ... I don't think there's a Lazy Susan at the Otis, but that tends to be the way things are done in the Labor Party.

"They go off to lunches, they make deals, and it seems the leader of the opposition has a few things to explain."

Australian Associated Press