Ultra Electronics has suffered another blow, revealing it is being investigated for suspected corruption by the Serious Fraud Office.

The defence and technology group said it had reported itself to the watchdog and the matter concerns the “conduct of business in Algeria by Ultra, its subsidiaries, employees and associated persons”.

The only public mention Ultra has made of Algeria in recent years is in the 2015 annual report, which referred to the company’s “TCS division expanding in Africa, receiving its first contract from Algeria”.

The TCS division provides communication and control services such as high capacity radios, as well as “electronic warfare” systems such as signal jamming. However, the company refused to comment on the exact nature of the affected work though it is though to involve sales to a second party who then sold the equipment on to a buyer in Algeria and involves support services work.

Work in Algeria is said to represent “a speck” - understood to be less than £500,000 last year - in Ultra’s annual revenues of £775m, falling into the rest of the world arm which makes up 17pc of all sales.