The US investigation into bribery allegations involving British defence firm BAE Systems has stepped up a gear, with the detention of two senior executives by US authorities.

Chief Executive Mike Turner and Non-Executive Director Sir Nigel Rudd were detained and issued with subpoenas by officials from the Department of Justice (DoJ) as they landed at Houston airport, the Financial Times reports.

They were kept for about half an hour and had their documents and personal electronic equipment examined.

The DoJ is probing the £43bn al-Yamamah arms deal under which Saudi Arabia bought aircraft and other defence equipment from Britain in 1985.

The US inquiry began after Britain ended its own Serious Fraud Office (SFO) investigation into the allegations in 2006 at the behest of the government.

Earlier this year, the High Court ruled the SFO had acted unlawfully in abandoning the case.

BAE says the DoJ had served “a number of additional subpoenas in the US on employees of BAE Systems plc and BAE Systems Inc as part of its ongoing investigation, which the company has previously announced”.

“The company has been and continues to be in discussion with the DoJ concerning the subpoenas served in the course of its investigation.”

BAE declined to comment on the details of the subpoenas but stressed that neither man was prevented from entering the US and that Turner has returned to the UK.

By Elizabeth Clifford-Marsh