Yet, despite the rapid growth of the private security sector, which now employs an estimated 20 million documented personnel worldwide, these staff hold far fewer firearms than do state security forces, the annual Small Arms Survey reveals.

The 2011 edition of the survey, published today by the Graduate Institute of International and Development Studies in Geneva, finds that private security staff personnel in 70 countries measured hold no more than four million firearms, compared to 26 million held by police and law enforcement officials, and 200 million held by members of national armed forces.

The survey notes that regulation and accountability mechanisms have not kept pace with the surging growth of the private security sector, which is increasingly likely to be responsible for security at airports, along borders, in prisons and on public streets.

“Despite evidence that some private security companies have engaged in the illegal acquisition of firearms, have lost weapons through theft, or have misused their arsenals, there is no systematic reporting of such misconduct,” according to a press release issued by the survey’s authors.

Many multinational corporations do not have oversight systems that are strong enough to prevent the hiring of private security personnel known to have used excessive force in the past, the survey finds.

The annual overall trade in light weapons, small arms and their ammunition is now estimated at nearly $7.1 billion, with the top exports in 2008 being the United States, Italy, Germany, Brazil, Switzerland, Israel, Austria, the Republic of Korea, Belgium and Russia.

The top importers in the same year were the United States, Canada, the United Kingdom, Germany, Australia, France and Pakistan.

Funded by several governments, the Small Arms Survey is an independent research project that draws upon data from UN Comtrade, a database maintained by the UN Statistics Division, and the UN Register of Conventional Arms.