Portuguese detectives have arrested four police officers suspected of assaulting Nepalese immigrant workers in the country's latest allegations of police misconduct.

The Policia Judiciaria, which investigates serious crimes, says Wednesday the four arrested men belong to the Guarda Nacional Civil, a paramilitary police force which has jurisdiction in rural areas.

They are accused of assault in what local media reported was a dispute with the Nepalese workers.

Portuguese officials say authorities last year received 860 complaints of misconduct against police officers — the highest number for seven years. That also includes complaints against the Policia de Seguranca Publica, which patrols urban areas.

The General Inspectorate for Internal Affairs, which monitors the police, says it is currently checking the possible presence of far-right groups in the security forces, following specific complaints.