British police were roundly criticised on Wednesday for arresting journalists as they covered disruptive environmental protests.
A radio reporter, photographer and documentary maker were detained on Monday and Tuesday as they reported on the demonstrations near London.
Activists from the Just Stop Oil group chained themselves to gantries over the busy M25 orbital motorway, snarling traffic.
Charlotte Lynch said she was arrested on a nearby motorway bridge, despite showing officers her police-sanctioned press card.
The LBC radio reporter said she was handcuffed, taken to a police station and held for five hours before being released without charge.
"The only question was how I knew to be there," added Lynch, who said she was held on suspicion of conspiracy to cause a public nuisance.
"I was just doing my job," she added, calling it a "terrifying" assault on press freedom.
"It was blindingly obvious I was a reporter."
All UK press cards carry wording saying that the National Police Chiefs' Council "recognise the holder... as a bona fide newsgatherer".
It also provides a phone number for officers to check accreditation.
The two other journalists said they had their equipment seized while one said officers searched his house.
Forces responsible for policing areas the motorway passes through have been criticised for pre-emptively arresting Just Stop Oil protesters.
The group, which wants an end to UK oil and gas exploration, has caused weeks of disruption in London with high-profile direct action protests.
Hertfordshire Police defended its actions, saying it had "grounds" to hold the journalists in custody "in order to verify their credentials and progress our investigation".
Britain's National Union of Journalists (NUJ) though called it a "breach of journalists' rights" to report to the public accurately.
"Journalists have every right to protect sources and should not be pressured into revealing private communications," it added.
"A press card presented by any journalist to police officers should be respected, and any effort to undermine journalists' work ultimately threatens press freedom."
Shami Chakrabarti, the former head of the civil liberties group Liberty, called the arrests "very, very serious".
"If the police are now going to start arresting journalists for conspiracy to commit a public nuisance -- in other words for knowing a demonstration is about to take place -- then they are effectively shutting down the free press," she told LBC.
Right-wing interior minister Suella Braverman has promised police greater powers to crack down on "guerilla" protest tactics that bring "chaos and misery" to the public.
But the government's education minister Gillian Keegan said: "Journalists shouldn't get arrested for doing their job."
