Estimates on the number of private security contractors working in Iraq vary widely, but the figure could be as high as 20,000.

That makes "hired guns" the second largest source of firepower in the country, after the US army.

Most private security guards are former soldiers - many of them ex-special forces - or former law enforcement personnel who have had experience of firearms.

British security consultancy Hart Group currently has up to 40 international staff and locals working in Iraq.

That has fallen from a peak of 200 and 2,000 respectively, as businesses have withdrawn their operations in the face of worsening security.

Chief operating officer Graham Kerr said: "Most of our people have had some capture training and they're fully aware of risks.

"Nobody is coerced into going to Iraq."

Private security guards are, however, lured by financial rewards, with payments of up to £1,000-a-day not unheard of for the most dangerous roles.

Government protection

Mr Kerr said it was important to distinguish between private security companies like Hart, and private military companies.

The former carry out essentially defensive, protective work while the latter are more often associated with the offensive roles of militias and mercenaries.

"We're not the dogs of war going in to overthrow the government. We're not in that business at all," Mr Kerr said.

"Basically speaking, our business is the protection of resources and assets, and the prime resource of any company is its people."

As well as personal, bodyguard-style security for individuals, private security companies carry out two other main duties.

The first is the protection of loads and logistical movements - meaning convoy escort work.


We're not the dogs of war going in to overthrow the government
Graham Kerr
Hart Group

The second is to provide "static guards" for camps, buildings or equipment involved in Iraq's reconstruction.

This could be in the centre of a city like Baghdad or out in the desert.

Some security contractors are hired by media organisations to help journalists move around Iraq as quickly and safely as possible - often to reach rather than avoid the flashpoints.

Other private security guards work for the Iraqi authorities or individual British government departments, such as the Foreign Office, the Department for International Development and HM Customs & Revenue.

The Foreign Office, for example, has contracts with two companies in Iraq - Control Risks Group to guard its people and Armor Group to protect its buildings.

Armor Group also works with firms like BP, Exxon Mobil and Bechtel who operate in some of the world's trouble spots.

It provides advice on how to minimise the risk of kidnap and extortion and where necessary, assists with dangerous tasks like landmine clearance.

'Little experience'

There have been complaints by some private security staff that they are doing an Army-style job, but with poorer equipment and training.

Others are concerned that some firms do not have strict enough vetting procedures for staff, or sufficient training to allow them to work safely.

Robin Horsfall, a former SAS officer, told the BBC that soldiers feared private contractors almost as much as insurgents in Iraq because they were basically "civilians with very little experience".

And he said he believed the tendency was to give them no additional training to cope with the situation in Iraq and to rely instead on whatever experience they already had.

There is currently no statutory regulation of UK or US private security companies, but most insist they set their own rigorous ethical standards.