Top police officers were quizzed on Friday about whether the force “criminalised protesters” at last year’s anti-fracking demonstrations in Balcombe.

Sussex Police and Crime Commissioner Katy Bourne asked acting Chief Constable Giles York whether police had learned from the controversial protest policing, which saw many of those arrested acquitted.

Concerns have also been raised by the solicitor who represented many of the protesters in court, that the mass arrests were used as a tactic to criminalise protesters.

A total of 126 people were arrested during 62 days of protests in Balcombe last summer in an operation costing £4 million.

A total of 43 people have been acquitted, among them MP Caroline Lucas, leading to criticism of the operation.

Many protesters were arrested after police issued a Section 14 notice under the Public Order Act, which gives the power to arrest if protesters ignore conditions imposed by the force.

Lydia Dagostino, of Kelly’s solicitors in Brighton, said: “Balcombe was a turning point in the policing of protests as it was the first time Section 14 was used as a mass arróest technique, which resulted in peaceful protesters being arrested and taken through the court system for many months before being acquitted.

“The concern is that this has criminalised protest."

Ms Bourne, speaking at a performance and accountability meeting yesterday, said: “My concern is, have police learned from this?

“If you go on Google there are blogs from four years ago with similar stories about the use of Section 14. Are forces actually learning?

“The other issue is that the arrests were made as a tactic to criminalise protesters.”

Mr York replied: “We’ve got no interest in criminalising protesters.

“It’s incredibly difficult to strike that balance between facilitating legitimate protest and upholding the law, but it’s a balance we are seeking to strike.”

According to Freedom of Information requests by a national newspaper to Sussex Police and the Crown Prosecution Service, only 90 of the 126 people arrested were charged.

The last of the criminal trials finished this month, resulting in only 29 convictions.