Chris Packham has said he has reached the point where he feels it is “ethically responsible” to break the law to protect the climate.
Tory MP Gary Sambrook criticised Packham and said it was time to call people like him "deluded".
It came after Rishi Sunak faced fierce criticism after weakening a host of environmental pledges.
A Tory MP has branded Chris Packham an “ideological zealot” after the environmentalist admitted he was willing to break the law in the fight against climate change.
In his new Channel 4 documentary Chris Packham: Is It Time to Break the Law? the presenter said he had reached the point where he felt it was “ethically responsible” to commit some crimes to protect the environment.
He said: “If you’re an activist that’s made a decision to break the law, as long as no one is hurt and there’s no lasting environmental damage. Then you’ll have my support.
“And personally, I think I’ve reached a point where I now consider it the ethically responsible thing to do.”
But he stressed he was not asking anyone else to break the law and there were plenty of legitimate ways to protest, including signing petitions, going on marches and lobbying politicians.
Birmingham Northfield MP Gary Sambrook criticised Packham for his comments.
He wrote on X (formally Twitter): "Ethically, I think it’s right we should start calling out people like @ChrisGPackham as deluded ideological zealots who will cause damage to livelihoods without a care for ordinary families."
It followed criticism from home secretary Suella Braverman, who said on Good Morning Britain (GMB): "I totally refute what Chris Packham and organisations like Just Stop Oil stand for.
"They take a militant, aggressive approach to prosecuting their cause. Totally unacceptable."
GMB presenter Richard Madeley also condemned Packham during his appearance on the show, drawing parallels between him and the IRA.
He added: "They (IRA) believed in it passionately with all their heart and soul and were prepared to risk an army bullet for the sake of the cause. It was their choice to break the law and they had to take the consequence."
Watch: Richard Madeley challenges Chris Packham over campaigning
Packham's comments defended
Will McCallum, Co-Executive Director at Greenpeace UK, said: "Some of the most progressive moments in history - from ending slavery to votes for women, Indian independence and rights for Indigenous peoples - were only achieved by breaking the law.
"Given the gradual erosion of civil liberties in this country, it is telling that it takes an excellent documentary by Chris Packham to remind us that civil disobedience and the right to protest are essential parts of a healthy democracy.
"It is a surprise that the question needs to be asked at all."
Packham also received significant support online, including from Alice Roberts, professor of public engagement in science at the University of Birmingham.
She wrote: “Neither Channel 4 nor Chris Packham condone breaking the law, which was very evident in this programme.
“Instead, the programme posed a very personal question, urging each of us to consider the morals and ethics carefully. And the changing parameters of our UK law around protest as well as examples from history - such as Emmeline Pankhurst - were also carefully considered.”
In the documentary, Packham looks at the climate crisis from his perspective and questions whether it's worth breaking laws considering other methods are not working.
The fallout from Packham's comments come after Prime Minister Rishi Sunak faced fierce criticism in some quarters for weakening a host of pledges designed to help the UK reach net zero by 2050.
He pushed back a ban on new petrol and diesel cars by five years and watered down the plan to phase out gas boilers by 2035.
King Charles branded global warming “our most existential challenge” a day after Sunak's decision to scale back key green efforts to tackle the climate crisis.
The King made the remarks in a historic address during his state visit to France as he became the first British monarch to speak in the French senate chamber.
Climate protests have become an increasingly common occurrence in the UK from groups such as Just Stop Oil and Extinction Rebellion.
However, in May, anti-protest laws that bolster police officers' powers to tackle protesters were rolled out.
The new rules include up to 12 months in prison for protesters blocking roads, airports and railways, and up to six months behind bars for protesters "locking on" to others, objects or buildings.
The former shadow attorney general, Shami Chakrabarti, highlighted issues with the new rules, including the broad term "locking on".
She told the Guardian: "During the passage of this illiberal and headline-grabbing legislation, ministers admitted that the new offence of ‘locking on’ is so broad as to catch peaceful protesters who link arms in public."
The government previously said: "This government fully supports the right of individuals to engage in peaceful protest; however, the serious disruption caused by a small minority of protestors has highlighted that more needs to be done to protect the public and businesses from these unacceptable actions.
"These new measures are needed to bolster the police’s powers to respond more effectively to disruptive and dangerous protests."