Sussex Police gave insufficient warning to peaceful anti-fracking protesters before arresting them, a court was told.

Eleven campaigners are standing trial accused of obstructing the highway during protests against drilling firm Cuadrilla.

The activists were arrested in Balcombe on July 26 outside the drill site gates after being warned they were blocking the access for emergency services.

But defence lawyers told Brighton Magistrates’ Court yesterday that police officers did not give enough warning before making arrests.

Paul Deacon, 50, formerly of Selden Lane, Worthing; Samantha Duncan, 30, of Beaconsfield Villas, Brighton; Ian Freeston, 52, of Phoenix Place, Lewes; Ezra Lynch, 31, of Phoenix Place, Lewes; Mark Mansbridge, 51, of Paddock Road, Lewes; Richard Millar, 30, of Upper Gloucester Road, Brighton; Michael Atkins, 37, of Westbury; Frances Crack, 31, of Cardiff; Justin Preese, 44, of Pontypridd; Marcin Swiercz, 35, of London; and Nancy Walker, 25, of London all deny wilful obstruction of a highway.

Atkins is also accused of assaulting a police constable by throwing tea at her.

Opening the prosecution case, Jonathan Edwards said that a large tree trunk was dragged in front of the gates to the site being test drilled by Cuadrilla, off London Road, which protesters sat on to block access.

The court saw a video of police officers warning protesters that they were breaking the Trade Union and Labour Act by disrupting a workplace.

Pressure point techniques were used to force the protesters apart, with onlookers shouting “shame on you!”

Chief Inspector Matthew Webb, commander of police on the ground at Balcombe, said the site was a “hazardous working environment” and needed 24-hour emergency service access.

But he accepted that after arriving at Balcombe at 9am to the log blockade, he did not warn protesters to move until midday, shortly before ordering a first round of arrests. After a second warning he said he ordered further arrests.

Shahida Begum, one of the defence lawyers, said: “Nowhere in your statement does it say you instructed police liaison officers to have formal discussions with protesters. There was no engagement.”

CI Webb said: “If the protesters had not heard my warning then that was because of the noise they were making themselves.”

District Judge William Ashworth must decide if there was an obstruction, if it was wilful and without excuse, and if prosecution was a reasonable response.

The trial continues.