Two top BAE Systems executives have been detained by US authorities probing corruption allegations.
The defence firm's chief executive, Mike Turner, and a senior colleague are understood to have been held as they arrived in America on business this week.
The pair were released after being questioned and having documents and personal electronic equipment - including laptops and Blackberries - examined.
The US Department of Justice acted at Houston airport in Texas, as part of its investigation into a £43 billion arms deal between BAE and Saudi Arabia.
The company has been accused of making illegal payments to key officials from the regime - although it has repeatedly denied any wrongdoing.
There was outrage in December 2006 when the British Government announced that the Serious Fraud Office was dropping its probe into the al-Yamamah deal.
The then-Attorney General, Lord Goldsmith, and PM Tony Blair insisted continuing would have caused "serious damage" to UK-Saudi relations and put national security at risk.
However, the High Court has since ruled that the SFO acted unlawfully in abandoning the case, while the American authorities have pressed ahead.
According to the Sunday Telegraph, several US-based BAE executives had their homes raided at around the same time Mr Turner and his unnamed colleague were detained.
British officials in Washington were reportedly informed of the incident on Monday when Mr Turner, a 59-year-old father of four, alerted military contacts at the Embassy.
