What he discovered has led, seven years on, to moves in Britain to investigate Smith — a pillar of the community in the peaceful Wiltshire village where he lives — for possible war crimes.

The conflict in the Democratic Republic of Congo (DRC), which had drawn in troops from six African nations, was of huge concern to the UN. By the time the war ended in 2003 more than 3m people had died. The civilian toll was the highest anywhere since the second world war.

Pelham, an Irishman, was acting as an undercover investigator for the UN security council. He had been sent to the Congo to find out about the activities of another company that was believed to be trafficking in illicit weapons and diamonds.

Instead he reported back to his controller on the activities of the company employing him.

Avient’s role was supposed to be logistical but Pelham says he was put in charge of helicopter gunships and civilian aircraft that had been converted to drop bombs and were being flown by Avient crews.

Under a crewing agreement Smith had signed with General Joseph Kabila, the future president of the Congo, on September 21, 1999, Avient undertook to provide aircrew who would “operate along and behind the enemy lines in support of ground troops and against the invading forces”.

Pelham claims he found that Ukrainian and Russian aircrews recruited by Avient on behalf of the Congolese airforce were flying blanket bombing raids that in all probability were killing and maiming civilians caught in the war zone thousands of feet below.

Rudimentary bombs made from industrial gas cylinders filled with TNT were being rolled out of the backs of giant Antonov transport aircraft flown at high altitude in indiscriminate raids, according to Pelham.

The crewing agreement signed by Smith and Kabila noted that Avient was acting as an “intermediary to facilitate the supply” of aircrew and said the company could not be held accountable for the individual performance of crew members.

Pelham says that the reality was different. He alleges that Avient was providing crews for aircraft involved in military activities, including Antonovs and an MI-24 attack helicopter gunship, and that Smith knew what they were doing.

“I was reporting to him and he was completely aware of what was going on,” Pelham said. “It was not the government coming to Smith and saying, ‘Can we use these aircraft for these missions like this?’ It was, ‘You have got a problem. You do not have helicopter support and you do not have military aircraft support. Let us assist you. We will run that for you’.”

At one point, he claims, he tried to put a stop to the bombing by informing Smith that he was not happy about the missions. But he says in a sworn affidavit that Smith replied: “This is what Avient is there for and it is part of the fun of Avient’s activities.”

Explore UK News

• Science News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Savers left in limbo as Icesave freezes deposits
• Kennel Club changes breeding rules
• Passengers triple risk of fatal crashes