The far-right agitator Daniel Thomas has denied causing criminal damage after he was filmed appearing to slash a boat in the Channel with a blade, while an emergency responder was onboard.

Thomas, 37, appeared at Basingstoke magistrates court on Friday morning. He also pleaded not guilty to not disclosing to police the pin number of his phone, under section 53 of the Regulation of Investigatory Powers Act 2000.

Prosecutor Kevin Lucie, outlining the basis of the criminal damage charge, alleged Thomas slashed an adrift boat with a knife.

Thomas, also known as Danny Tommo, was refused bail. The father of four, described as a professional roofer, was seen dabbing his eyes with a tissue at one point during the hearing.

Thomas appeared for the hearing via video link. He was supported in court by his fellow far-right activist Stephen Yaxley-Lennon, also known as Tommy Robinson. Other supporters were placed in a separate room to watch a live stream from the court, a routine measure when interest in a case outstrips the space available in a courtroom.

There was also a visible police presence, with an officer in the public gallery of the courtroom, another at the courtroom door and yet another in the seated waiting area outside the courtroom.

On Thursday evening, several hundred people – many wearing black – gathered outside a police investigation centre in Basingstoke, apparently in the belief Thomas was inside. Dozens of police officers could be seen monitoring the group outside the investigation centre as the protest continued for several hours.

Thomas has said he would like a crown court trial. A hearing will take place in Portsmouth crown court on Tuesday 29 September.