Aegis Defence Services Ltd., a British company that is one of the largest private security contractors in Iraq, is conducting an investigation into whether the firm's employees are involved in video clips circulating on the Internet that appear to show civilian vehicles being shot at.

In one of the clips, a vehicle is fired upon before crashing into another, and in another clip, a vehicle is hit before it veers off the road and stops. Music is playing in the background. While the clips are labeled "Aegis PSD," no company insignia or identifying information is visible. The clips leave it unclear just who -- whether troops, contractors or other civilians -- might have been doing the shooting.

The clips were originally posted on a Web site, www.aegisIraq.co.uk, according to overseas media reports, but have been removed. According to a posting on the Web site, the site is not owned by Aegis and "belongs to the men on the ground who are the heart and soul of the company."

"Aegis has established a formal board of enquiry in cooperation with the U.S. military authorities to investigate whether the footage has any connection with the company and should this provide to be the case under what circumstances any incident took place," according to a company statement issued Monday.

The firm has been controversial because its chief executive provided military assistance to warring factions in Asian and African conflicts in the late 1990s.

The Aegis statement also said military and State Department rules allow for "a structured escalation of force to include opening fire on civilian vehicles," if, for example, "there is reason to believe that an escort vehicle is under imminent threat of attack by vehicle-born suicide bombers." All such incidents are investigated by the company, the statement said.

Maj. Tim Keefe, spokesman for Multinational Force-Iraq, which operates under U.S. Central Command, said, "U.S. military authorities are looking into the matter."

The three-year-old British firm said it has about 2,000 employees in Iraq and has opened an office in Afghanistan.