Commons Speaker John Bercow has told MPs he has no problem with them referring to the DUP as a bunch of "dinosaurs".

Bercow made the official ruling after Green party co-leader Caroline Lucas spoke out in the Commons.

Addressing Theresa May, Lucas said: "It’s good to see her here, actually facing the other parties. She has actually turned up, which was not always the case in the election campaign."

Moving on to the Queens Speech, she added: "The speech contained eight Brexit bills, but not a single one of those bills covered the environment.

"Is her failure to propose a Brexit bill on the greatest challenge that we face because she simply doesn’t care about the environment and climate change?

"Or because she’s been influenced by the DUP dinosaurs who sit beside me?"

This time the Prime Minister actually bothered to turn up, but it seems she's been influenced by DUP dinosaurs. @CarolineLucas #QueensSpeech pic.twitter.com/YA2BlxaSnH — Green Party (@TheGreenParty) June 21, 2017

An upset DUP MP Jeffrey Donaldson then asked: "Is it parliamentary for the honourable lady to describe us in the unparliamentary terms that she did, which I regret? She does not understand the policy that my party has on the environment."

But Bercow told Donaldson he would have to get used to it. "The use of the word in question is not unparliamentary, it’s a matter of taste as to its desirability," said the Speaker.

To cushion the blow, he added: "The word in question refers to a species that survived for many millions of years."

While climate change scepticism is not official party policy, the words 'environment' and 'climate change' do not appear in the DUP's 2017 general election manifesto.

In 2008 the DUP appointed climate change denier Sammy Wilson as environment minister. And in recent years they have resisted attempts to introduce an independent environmental protection agency, instead proposing to introduce an advisory division within the environment department.

Friends of the Earth Northern Ireland director James Orr said: "There have been a series of attempts to get climate legislation here over the last ten years. The DUP are the most reluctant party to embrace greenhouse gas reduction targets."