A dentist society in Nakhon Ratchasima has again asked police to arrest a German man they accuse of repeatedly assaulting their members in their clinics and damaging their equipment.

Spokesman Wiwat Chatwongwan went with other dentists who say they have been attacked to file a complaint with police on Monday.

Mr Wiwat said the society wanted police to take legal action against the man, a 41-year-old German.

They allege the man has attacked several dentists in clinics in the area since November last year.

One dentist had filed a police complaint in November, but there was no progress in the police investigation. In the meantime, the man had attacked several other dentists in their clinics, Mr Wiwat said.

Security cameras had recorded the man's visit to a dental clinic on the evening of Nov 30 last year.

After seeing the dentist and returning to the ground floor the man appeared agitated, rushed up to the second floor, punched a hole in the door of a surgery occupied by a woman dentist and opened it. He went inside and grabbed the dentist’s head, bit her lips and knocked her head against a wall before leaving.

The most recent attack was at another dental clinic, this one in a shopping mall, at 5.34pm last Friday.

Mr Wiwat quoted the man’s wife as saying her husband had mental issues.