Two former British arms manufacturer chiefs have been jailed for paying bribes to secure multimillion-pound contracts for the supply of military equipment to armed forces in Afghanistan.

Robert Gillam, 66, of Corfe Castle, Dorset, and his business partner Simon Davies, 46, of Ringwood, Hampshire, admitted corrupt payments and were jailed for two years and 11 months respectively at the Old Bailey.

Their dealings were uncovered by a joint investigation involving the City of London Police, the Federal Bureau of Investigation (FBI) and Special Inspector General for Afghanistan Reconstruction.

Investigators discovered a series of bribes made by the UK company Mondial Defence Systems Ltd for contacts worth more than five million dollars with US company Ronco Consulting Corporation, a supplier to the US government.

The money went to Ronco's operations manager Robert Gannon to secure the supply of military items such as de-mining equipment to forces based in countries including Afghanistan and Iraq.

Detectives found the contract between Mondial and Ronco was awarded at the same time that Davies and Gillam made two payments - one of £72,000 and one of 75,000 US dollars - into Gannon's personal off-shore bank account.

One email Gillam received from Gannon on Christmas Eve 2009 followed a personal payment of 75,000 US dollars.

It said: "Bob Great news - this seems to have done the trick - santa left his parcel. Much appreciated. Here is to 2010 being a good year."

In November 2015, Gannon, a British citizen who had a house in Scotland, was jailed in the US for a year for conspiracy to accept a kickback.

Detective Sergeant Joanne Ferguson said: "Mondial were a small company which used dishonest and corrupt practices to get ahead in business, stealing opportunity from honest competitors.

"This type of crime harms the reputation of UK business making it impossible for genuine businesses to compete, ultimately causing a ripple effect which not only affects the UK economy but local businesses as well."

Stephen Rowland, of the Crown Prosecution Service, said: "Bribery is a crime with a corrosive effect. It impedes the prospects of honest business competitors and can ultimately cost jobs and livelihoods.

"Evidence including bank accounts and email correspondence discussing the payments was presented by the prosecution to demonstrate a compelling case, leaving these men with no option but to plead guilty.

"These sentences send a clear message that bribery can and will be successfully prosecuted by the CPS."

Gillam was disqualified from being a company director for five years and Davies for two years. The pair now face confiscation proceedings.