MORE than 50 former police officers have joined the auxiliary police force this year, a top part-time officer said yesterday. The Deputy Commandant of the Auxiliaries, Mr Peter Chau Cham-chiu, said an average of 10 former police officers had been recruited into the part-time force each month this year. And he defended the auxiliary force's policy of writing to each officer who was about to leave the Royal Hongkong Police. Mr Chau said: ''The letters we send to police officers about to leave points out that they should consider serving in the auxiliary force when they finish their service. ''We do not write to officers who have not declared that they are getting out. These are people who have said they are leaving, and we would like them to consider using their experience to the benefit of the Royal Hongkong Auxiliary Police Force. ''I am a former full-time policeman myself and had to leave the force because my brother died, and I was needed to carry on his business.'' Mr Chau added that the police officers left the full-time force for various reasons and pay was not the only factor. It was likely that more former officers would be recruited this year despite the auxiliaries being at their full strength of 5,746 men and women. He said the auxiliary force had a waiting list of more than 500, including other ex-police officers. Police chiefs hoped that last year's 42-point plan that improves pay and conditions for junior officers would help reduce the trend of full-time officers leaving the force for the auxiliaries. In 1991, 82 officers who had left the full-time force were recruited into the auxiliaries. About 750 auxiliary officers are deployed each day to either patrol Hongkong's streets or take up duties to relieve police clerical staff. Mr Chau said new recruits included men and women who had returned to Hongkong from abroad, as well as local people from professional occupations.