One of two British men recently assaulted by security guards at a bar in Pattaya filed a complaint with police, while his friend did not report the attack due to safety concerns.

Police said on Wednesday that officers found the two foreigners shown in viral video clips of the assault and asked them to provide statements and file a complaint against the attackers.

The other foreigner, a friend of the two Brits, had already left Pattaya for Bangkok, police said.

Police on May 26 arrested three security guards involved in the assault at Helicopter Bar Soi 6 at about 5pm on May 24.

Police said the three guards confessed to the crime. One guard said a foreign customer shoved and punched him first, breaking his nose and requiring six stitches. The guard apologised, saying he and his colleagues lost control and overreacted.

The brawl was recorded by onlookers using mobile phones. Videos showed a security guard being attacked first. The three guards then retaliated.

Mr Bryce Mahoney, a 42-year-old British national, sustained bruises on his face, head and body.

He told police that the assault occurred on his birthday on May 24. He and his two other friends had been drinking at the bar since noon. After drinking, a dispute over the bill payment escalated into violence.

Mr Mahoney filed a complaint against the guards. His friend, who was also assaulted, did not file a complaint due to safety concerns if he stayed in Pattaya, according to police.

A police source said the attackers had not undergone any security guard training from any security firms or state agencies. Police were investigating further and would file more charges if other offences were found.