The arrest of a man in Rotorua in 2019 has been ruled unlawful by independent investigators.

The Independent Police Conduct Authority has found police unlawfully arrested a man for disorderly behaviour in Rotorua on November 18, 2019.

Officers had seen the man riding his bicycle without a helmet and stopped to talk to him.

The man became abusive towards the officers and was arrested.

The man resisted the arrest and one of the officers put him into a headlock to restrain him.

The Authority found the man's behaviour was a direct response to the police stopping to talk to him.

The IPCA says the facts and circumstances did not give sufficient grounds for police to suspect the offence of disorderly behaviour had been committed.

'It then follows that any force used during the arrest process was also unlawful. Notwithstanding, the use of the headlock was also excessive.”

The authority also found some unnecessary and excessive pressure was applied to the handcuffs while they were on the man, which caused him an injury.

'The actions of the officers were not only unlawful but undesirable and counterproductive to the Commissioners intent of 'Policing by consent' and 'to have the trust and confidence of all',” says authority chair Judge Colin Doherty.

A police spokesperson says police acknowledge findings of IPCA into use of force during arrest.

'The staff involved were spoken to after the arrest.”