Investigators have spent a second day searching two offices of the engineering firm Alstom as part of a corruption inquiry.

The properties in Rugby and Ashby de la Zouch were raided earlier this week, along with seven other addresses, after a Serious Fraud Office (SFO) investigation.

The company’s president and two senior directors were freed without charge after being questioned by police on suspicion of bribery and corruption.

The three – named by company spokesman Stephane Farhi as president Stephen Burgin, finance director Robert Purcell and legal director Altan Clidwyn-Davies – were arrested by the Serious Fraud Office (SFO) on Wednesday.

An SFO official confirmed they were released on police bail.

The arrests related to allegations of bribery and corruption, conspiracy to pay bribes, money laundering and false accounting.

The investigation centres on suspected bribes paid in the UK to influence the awarding of overseas contracts to companies in the Alstom group.

A statement on Alstom’s website read: “The police have apparently executed search warrants upon the Swiss Federal justice request.

“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 co-operating with the British authorities.”

Officers from several UK forces and the Swiss Federal Police have been involved in the investigation.

SFO director Richard Alderman said: “We are working closely with other criminal justice organisations across the world and are taking steps to encourage companies to report any suspicions of corruption, either within their own business or by other companies or individuals.”