The UK Serious Fraud Office can restart its bribery investigation into Alstom after the courts refused a legal challenge from two of the engineering company's directors.

Stephen Burgin, Alstom's UK president, and Robert Purcell, its finance director, were trying to challenge the way the SFO had conducted dawn raids on their homes last March.

While their case was in process, SFO investigators were banned from reviewing any of the evidence they had seized in the raids.

The two men had applied for the courts to review the legality of search warrants used by the SFO. There were no reasonable grounds for the raids and the warrants were incomplete and lacked necessary information, they argued. They also claimed they were arrested without reasonable grounds for suspicion.

Their request was rejected this week on all grounds.

Lawyers said the result was a significant victory for the SFO, which has been criticized for its use of dawn raids.

No charges have been made against the men and the company denies any wrongdoing.