Police yesterday said they were treating as a complaint the threat of legal action made by the chairman of the Hong Kong Football Association over his arrest in an assault case. Senior Assistant Commissioner Fung Siu-yuen was responding to a letter from Martin Hong Po-kui, 52, who demanded a public apology over his arrest. He claimed it was made without sufficient grounds. He was arrested on August 11 along with Canto-pop star Joey Yung Cho-yee, 21, for suspected involvement in an assault on RTHK disc jockey Leung Sze-ho on February 12. Mr Hong sent a letter to Police Commissioner Tsang Yam-pui last Thursday, warning of legal action unless the force apologised and cleared his name within a few days. He has also lodged another complaint with the police over his alleged wrongful detention. Mr Fung said the letter and the complaint had been passed to the Complaints Against Police Office, which would submit its findings to the Independent Police Complaints Council.