The Phuket governor condemned the New Zealand brothers who attacked a traffic policeman and stole his gun on Saturday, saying their serious violation of Thai law is completely unacceptable.

"Such an attack, no matter whether it happens to our officials or [ordinary] people, is intolerable," Phuket governor Sophon Suwannarat told a press conference at the Phuket provincial police office on Monday.

He was talking about two New Zealanders who attacked a traffic policeman on Saturday.

"The behaviour was improper and illegal... It sets a very bad example in a tourist province like Phuket... Serious action will be taken to protect the tourism atmosphere of Phuket... Visitors and Thai people in Phuket must be safe," the governor said.

The Phuket police chief said that Hamish Day, 34, and Oscar Day, 36, rode their rented motorcycles dangerously fast past the Chalong police station on Chaofa (West) Road at 4.10pm on Saturday, without using the left lane as required by law.

Pol Sen Sgt Maj Somsak Noo-iad, on duty in front of the police station, ordered them to stop but they ignored him. The policeman then pursued the two tourists and asked for a backup team via radio.

The visitors later stopped in front of a restaurant on Chaofa (East) Road. The policeman told them that they had violated traffic law for resisting his stop order. The policeman also asked for their driving licences.

At this point, the New Zealanders offered a bribe but the policeman rejected it and told them to pay their fine at the police station, the chief said.

In response, they walked towards their motorcycles. Somsak then used his mobile phone to take their pictures.

The brothers then became angry. One of them attacked the policeman, wrestled him to the ground and tried to take his gun.

During the struggle, the gun was fired once but no one was hit.

The attacker was a mixed martial arts fighter, the Phuket police chief said. He took the gun and handed it to his brother.

The backup team arrived a few minutes later.

The New Zealanders' tourist visas were revoked and they would be blacklisted.

A vehicle rental firm would be fined 2,000 baht for renting motorcycles to people without a driving licence, the chief said.