Johannesburg - There is large-scale inappropriate political interference in the police, which leads to a poor selection of leaders, the Institute for Security Studies (ISS) said on Tuesday.Head of the governance, crime and justice division at the ISS, Gareth Newham, told News24 that leaders in the police were being appointed despite their inability to do the job.Newham said President Jacob Zuma should only appoint a national commissioner after there has been a competitive merit-based and transparent recruitment process, to ensure that only the best were elected to do the job.He said until that happened, and until people were "being appointed because of their political loyalties", the police would not be able to function effectively.On Tuesday morning, Police Minister Fikile Mbalula released the 2016/17 crime statistics to Parliament's Portfolio Committee on Police.INFOGRAPHIC: SA's crime stats at a glanceMbalula admitted that the "chop and change" of police commissioners - from Bheki Cele who was dismissed over a maladministration scandal to Riah Phiyega, who was found to be unfit to hold office - had affected the focus and direction of the police.Mbalula had also slammed the "lazy efforts" of police to curb crimes.Also read: Crime Stats: Mbalula talks tough, slams 'lazy efforts' by policeHe said there had been a 1.8% decrease in crime during the 2016/17 financial year.Newham said the two most worrying crimes were murder and aggravated robbery.Murder had increased by 1.8% from 18 673 to 19 016 for the year ending March 31, 2017."In the last five years it went up by 22%. It shows that there is something seriously going wrong and the programmes and initiatives to reduce violence is failing," Newham said.Aggravated robbery increased by 6.4%.Also read: Crime stats in a nutshell — 2.1m serious crimes recorded in 2016/2017"There are 40 000 more cases of armed attacks in the country. It means on a day, on average, there are 110 more armed attacks than it was in South Africa five years ago," he said.Newham said crime statistics for categories such as the overall violent crime rate, sexual assaults, and sexual offences were all "highly unreliable" - because most of these crimes were not reported to the police."The fact that those numbers are going down is not a measure of violent crime going down, it is a measure of a greater number of victims not having faith in the police. Every year, fewer and fewer people report sexual offences and assault to the police."