LONDON, Nov.30: The prospect of the $ 10 billion British Eurofighter deal with Saudi Arabia collapsing because Riyadh had suspended negotiations is causing serious anxiety in the business and political circles here.

Asked how worried the prime minister was at such a prospect, the PM’s Official Spokesman said on Wednesday that he had not commented at all on the Saudi case because there was an ongoing case, and it would be wrong for him to do so. “Obviously, we were well aware of the case,” the PMOS added.

According to legal sources secret payments of millions of pounds from Britain's biggest arms company BAE have been found in Swiss accounts linked to Wafic Said, a billionaire arms broker for the Saudi Royal family.

Mr Said refused last night to speak to media about the allegations. But the discovery presents the biggest potential breakthrough yet achieved in the Serious Fraud Office's three year investigation into allegations that illegal commissions may have been paid to Saudi royals by BAE Systems. Details from the accounts would help to establish whether money was channelled to members of the Saudi ruling clan, and the amounts involved. The development comes amid threats from the company and its chief executive, Mike Turner that the SFO's ongoing inquiry threatens to damage the UK economy. He has claimed that the Saudi royal family may take a £6bn contract from BAE and give it to the French instead.

The company wants the SFO to abandon the investigation before the Saudis pull out of the deal for a new fleet of 72 Eurofighter Typhoons.

Speculation over the progress of the inquiry led to a dip in the company's share price earlier this week.

Both the Swiss legal authorities in Bern, and the SFO director, Robert Wardle, have been keeping their moves secret.

Swiss authorities said on Wednesday: “The office of the attorney general of Switzerland confirms being in charge of the execution of a request for mutual legal assistance in criminal matters from the UK serious fraud office relating to this case.” They and the SFO refuse to give any further details. But after Mr Said and other account-holders were alerted by the Swiss, he hired the City law firm Clifford Chance to represent him.

A series of British newspapers were briefed that the latest Saudi contract to buy Eurofighters was in danger and that the SFO should “put up or shut up”.