Security firm Westminster Group says it has won a 'multi-million pound' contract to supply mobile surveillance systems to an unnamed government security service.

It is the largest single contract Westminster has won and was achieved following lengthy consultation and assessment trials. The project starts now and will finish in the first half of 2011.

Chief executive Peter Fowler said: "It is excellent news, but because of the nature of the contract I cannot tell you where it is or how much it is worth, but it is considerable."

Mr Fowler led a management buy-out in the 1990s, when the Banbury-based company made burglar alarms, but it has since expanded into sophisticated electronic systems. More than 70 per cent of its sale are exports.

Before Christmas, the group issued a statement to the London Stock Exchange warning that cost-cutting measures were on the cards after declaring an operating loss of more than £2m for 2010.

But Mr Fowler said the company had known that several contracts were in the offing, particularly in the Middle East, but was forced by stockmarket rules to issue a warning.

He said Westminster was opening new offices in Qatar and Iraq in the next few months and was likely to expand its Banbury headquarters, which employs more than 40 people.