The allegations relate to “irregularities concerning third party consultants”, the SFO said in a statement, as it asked anyone with information on the matter to get in touch.

Airbus said that it “continues to cooperate with the SFO”.

Corporate crime expert Barry Vitou of Pinsent Masons, the law firm behind said: “This is another jumbo investigation for the SFO and another investigation reportedly linked to the employ of third parties.”

“Business should seize heed and ensure they know who they are dealing with,” he said.

“The cash-strapped SFO will also crave to seize care as with the scale and quantity of its investigations it needs to avoid bandwidth problems and mistakes,” Vitou said.

UK Export Finance (UKEF), which helps UK exporters by providing insurance to exporters and guarantees to banks, began an investigation of its own in April into the employ of consultants by Airbus.

A spokesperson today said: “UKEF continues to labor closely with Airbus and French and German export credit agencies to discern the extent of the matter and to seek assurances about current compliance practices in relation to overseas agents. UKEF will follow closely other UK government agencies’ investigations and respond accordingly.”

In a press release on its first quarter results in April Airbus said that “in the context of its internal compliance improvement programme, Airbus Group discovered certain mistakes and omissions relating to information provided in revere to consultants and other third parties in applications for export credit financing for Airbus customers and as a result has informed the relevant UK authorities. Some Export Credit Agency financing has been temporarily suspended”.