SINGAPORE - Almost half of the private security firms here performed poorly in an annual audit carried out by the police.

Of the 242 firms assessed, about 47 per cent were awarded the lowest grades of C and D. The results were, however, a slight improvement from the 50 per cent given the same grades in last year's audit.

Getting a C grade indicates a firm's performance was only satisfactory; a D means it was unsatisfactory.

This year, about 17 per cent of the firms were awarded an A or "excellent" grade, while 36 per cent got a B or "good" grade.

Five firms were exempted from this year's audit because they were newly set up.

The audit was introduced in 2006 and made mandatory three years later to help customers gauge a firm's quality. The companies are assessed on various aspects including employment standards, operations and human resource practices such as salary package.

Many security firms here say they face manpower issues, with most people shunning the long hours and low basic pay.There are 70,000 workers trained and qualified to work as security guards, but only 33,000 are actually doing so.

In October this year, it was announced that security guards will get higher wages from September 2016. The minimum monthly basic wages of security guards will rise to $1,100 from $800 under a new wage ladder announced by the National Trades Union Congress. The pay hikes will be done through the police, which regulates the security sector. The police will make the wage ladder compulsory as part of its licensing requirements for security firms from September 2016.