A journalist said she was handcuffed and taken into police custody for five hours after she was arrested while reporting on a Just Stop Oil demonstration.
LBC reporter Charlotte Lynch said she was on a road bridge over the M25 in Hertfordshire on Tuesday.
He said she was arrested on suspicion of conspiracy to commit a public nuisance, before being released.
Hertfordshire’s Chief Constable Charlie Hall said measures were now in place to allow legitimate media outlets to do their jobs.
Mrs Lynch said the incident was “absolutely terrifying”.
It comes after a photographer and a filmmaker said they were held in police custody for about 13 hours after they were arrested while trying to cover the protests earlier this week.
More protests took place on Wednesday.
The LBC reporter said she was arrested on a bridge between junction 20 (Abbots Langley) and junction 21 (M1/St Albans junction).
She said she showed officers her press card and explained she was reporting on the protest, but her phone was taken from her and she was arrested.
Ms Lynch said she was searched on the side of the road, before officers confiscated her devices and took her to Stevenage police station in a security van.
He said: “This journey took over an hour because the M25 was closed.
“I was in the back of a police van, my hands were in front of me, handcuffed the whole time, alone, the two officers were behind the glass cage.
“That’s when I thought ‘Oh my God, I could be charged here’ and it’s all going through your mind ‘have I really committed this offence?’ even though I knew I hadn’t.
“We got to the police station and I thought I’d answer their questions and go on my way.”
Ms Lynch said officers wanted to know how she knew about the protest.
He added that she was held in a cell for five hours before being released without further action.
“I burst into tears,” she said.
“I just couldn’t believe where I was. I felt like a criminal.
“It was absolutely terrifying to be in a cell with a pillow for a bed in one corner and a metal toilet in the other.
“I was just doing my job. What’s also scary is what this means for freedom of the press. It was blindingly obvious that I was a journalist.”
A statement from Hertfordshire Police said: “Our officers have been instructed to act as quickly as they can, using their professional judgement, to clear any potential protesters in order to open the roads and prevent anyone from being harmed.
“However, Chief Constable Charlie Hall acknowledges the concerns about the recent arrests of journalists who arrived at these locations and were present with protesters at the scenes. Additional measures are now in place to ensure that legitimate media can make the their work.
“Furthermore, Mr Hall is today calling for an independent force to review our approach to these arrests and identify any learning we need to take in managing these challenging situations.”
National Council of Police Chiefs Martin Hewitt said officers were under pressure when dealing with protesters but the media should not be prevented from reporting on them.
He said: “There is enormous pressure… but, of course, there is the right of journalists to go and report in these cases and that should not be prevented in any way.”
Ms Lynch said she was “delighted” the arrest would be looked into.
“I hope that what I went through and the ordeal I went through means that no other journalist has to go through it again,” he said.
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