Three members of the board of French engineering group Alstom in Britain have been arrested on suspicion of bribery and corruption.
The British Serious Fraud Office (SFO), which announced the arrests on Wednesday, has been working closely with the Swiss federal police.
The SFO said in a statement it suspected bribes were paid in order to win contracts overseas and that this had involved associated money laundering and other offences.
The three men arrested, who are aged 52, 51 and 44, were being interviewed at police stations, it said.
"The police apparently executed search warrants upon the request of the Swiss federal justice," Alstom said in a statement on its website.
"Alstom has been investigated by the Swiss justice for more than three years on the motive of alleged bribery issues. Within this frame, Alstom's offices in Switzerland and France have already been searched in the past years. Alstom is cooperating with the British authorities," the company said.
According to Swiss court documents released two years ago, the investigation centred on allegations that Alstom funnelled bribes worth SFr70 million ($65 million) a year through its Swiss subsidiary, hiding the payments as "consultancy fees." The company denies the claim.
"The Serious Fraud Office is undertaking its own investigation in England linked to Alstom businesses. The SFO is also executing a request from Switzerland for judicial assistance," said Jeannette Balmer, spokeswoman for Swiss federal prosecutors.
"In Switzerland, the Alstom investigations are ongoing. In light of the ongoing investigations, we cannot answer any questions on the substance of the case."
A related French inquiry was opened in 2007, based on information from Swiss authorities.
swissinfo.ch and agencies