Additional measures are being put in place to detect any early signs of mental stress faced by auxiliary police officers on the job.

Certis Cisco, which operates the largest auxiliary police force in Singapore with some 3,200 auxiliary police officers, said it will soon introduce talks for supervisors to help them better spot such problems early among their subordinates. This is in addition to the 28 para-counsellors already working in the company, said the security firm.

The security industry came under the spotlight recently when a 20-year-old Malaysian auxiliary police officer fatally shot herself in the head at the Supreme Court last month.

One day later, another Certis Cisco employee, an unarmed officer, was jailed for two months for pocketing a Cartier ring left behind by a passenger at the airport checkpoint he was working at.

There have been previous cases of officers pulling the trigger on themselves.

While the security company said the latest measure was not a reaction to the recent cases, questions have been raised about the screening and training standards of auxiliary police officers.

Some have questioned if standards have been relaxed in the face of the ongoing manpower crunch.

Auxiliary police officers not only carry firearms but are also vested with the power to arrest offenders. They are stationed at sensitive places such as immigration checkpoints and can perform roles such as escorting persons in custody.

Police figures show there are about 6,500 auxiliary police officers - up from fewer than 4,000 in 2005 - and 37,000 security officers in Singapore as of last December. The Government engages about 1,800 auxiliary police officers and some 1,200 security officers.

Currently, Singapore needs about 50,000 security guards, said Mr Robert Weiner, president of the Association of Certified Security Agencies. Industry players also said there is demand for another 1,500 to 2,000 auxiliary police officers.

A Certis Cisco spokesman said selection and training of its auxiliary police officers are stringent - they have to undergo a series of written tests and interviews after meeting the minimum requirements of physical and medical fitness.

This is after they have been approved by the police, who conduct security screenings and background checks.

Malaysian candidates, the only foreign nationality accepted for such jobs, also have to produce a certificate of good conduct issued by the Malaysian government. This is to ensure that the officers have a clean police record. These requirements are the same for the other two auxiliary police forces here, run by Aetos and the Singapore Airport Terminal Services.

Before firearms training starts, potential auxiliary police officers have to undergo a psychological and personality test, the same one used by the police and armed forces. Auxiliary police officers posted to single-man posts - such as remote locations and banks - are monitored by a wireless system that alerts an operations centre if their gun is unholstered.

The security firm said it frequently rotates officers sent to sensitive areas, to prevent them from becoming too familiar with the work environment and to minimise chances of them compromising on their jobs for favours. There are also annual checks on their financial health to ensure, for example, that they are not facing bankruptcy.

Still, those in the security industry said more can be done to take care of officers' mental well-being.

"When it comes to times of personal crisis, it all boils down to the individual, and how far he will go with what's available around him," said Security Association of Singapore president T. Mogan, adding that companies need to not only ensure that employees keep a lookout for each other, but also inculcate a daily self-reporting culture.

"In Singapore, officers have to pass a physical test but they don't do an annual mental test. There should be one," said the 22-year industry veteran.

Mr Hri Kumar Nair, chairman of the Government Parliamentary Committee for Home Affairs and Law, agreed that regular psychological testing should be part of a security company's culture for officers facing high-stress work.

He said: "It can be structured where there are sessions when auxiliary police officers can speak on a confidential basis to trained professionals... It's something they should be encouraged to go for on a regular basis, or made part of the employment contract."