Senator Milne’s comments came after a tweet by her colleague Lee Rhiannon, who publicly congratulated Jonathan Moylan, an activist who is the subject of an ASIC inquiry.

Mr Moylan sparked a sudden sell-off in Whitehaven shares on Monday when he released what appeared to be a press release from ANZ Bank.

ANZ arranged a $1.2 billion loan for Whitehaven in December to help the company build a new coal mine in New South Wales, but Mr Moylan's hoax email suggested that ANZ had gone back on its decision and would no longer lend the money.

‘‘Congrats to Jonathan Moylan, Frontline Action on Coal, for exposing ANZ investment in coalmines,’’ Ms Rhiannon tweeted on Tuesday evening.

Mr Moylan has admitted that to highlight environmental concerns he tricked investors into wrongly thinking that the ANZ loan for Whitehaven had been cancelled.

Shares in Whitehaven, which counts struggling coal baron Nathan Tinkler as its biggest shareholder, fell from $3.52 to $3.21 in rapid time before the stock was put into a trading halt.

Mr Moylan designed a fake ANZ press template, website and dummy email inbox online and impersonated a company spokesperson to callers, including Fairfax media. Moylan is now obtaining legal representation, and has received calls from ASIC.

Asked if he had qualms about lying to the public to achieve environmental ends, he said: ‘‘Our primary concern is the impact of this mine on the environment at the end of the day.’’

Senator Milne’s statement and Senator Rhiannon's tweet comes as the Greens try to appeal to new constituencies and recast themselves as less ‘‘extreme’’ in an election year.

Last month, the party revealed a new platform of policies aimed at presenting a smaller target to critics.

Senator Rhiannon's tweet has raised eyebrows on the social media site and exposed the Senator to ridicule.

‘‘Oh dear...what a ludicrously ignorant & idiotic tweet...from an office holder no less!’’ the commentator Rita Panahi wrote. Brisbane tweeter Cameron Loyd asked Senator Rhiannon: "What about mum & dad investors that lost money? Their fault for investing in coal?"

Simon Black, also from Brisbane, said: "I know greens [sic] can be a bit out there but openly endorsing breaking the law is breathtakingly odd."

But Senator Milne expanded upon her colleague’s comment.

"The two hottest days in Australian history have just been recorded and fires are burning around the country,’’ she said.

‘‘Companies that are driving climate change will increasingly come under scrutiny and be exposed for their investments and actions, and Jonathan Moylan is drawing attention to these companies. As with asbestos and tobacco, coal is going to come under increasing pressure.’’

Greens Communications Director Tim Hollo also defended Senator Rhiannon, replying to one of her critics on Twitter: ‘‘On the day @BobBrownFndn took on the leadership of Sea Shepherd, it's weird to attack @leerhiannon for defending the hoax.’’

Mr Hollo was referring to the announcement on Tuesday that former Australian Greens leader Bob Brown is to take over running the imminent Antarctic anti-whaling campaign by hardline conservationists Sea Shepherd, who are known for being violent and occasionally breaking the law to thwart Japanese whalers. His implication was that illegal tactics are often used to promote good causes.

Senator Rhiannon has previously seen controversy over her support for an anti-Israel boycott policy in the 2011 NSW State Election.

Last year, she apologised after it emerged she helped to ghost-write an opinion article, attacking her party for accepting a $1.7 million donation from the web entrepreneur Graeme Wood.

nationaltimes.com.au