Trafficmaster Plc has said its key vehicle satellite navigation system's performance was disappointing as it posted a first-half loss, sending its shares down 10% to a two-year low.

"We consider Smartnav's performance disappointing and will be taking action to improve the return from this business," new chief executive Tony Eales said in a statement cited by Reuters.

"We are also continuing to develop several new business opportunities including solutions for 'Pay As You Drive' insurance," added Eales, who Reuters noted has been CEO since July 20.

Trafficmaster reportedly made a pretax loss of £475,000 in the six months to end-June, on revenue up 16% to £19.7 million. The figures included a £563,000 provision for MG Rover bad debt. In 2004 Trafficmaster made a first-half pretax profit of £3.5 million.

An analyst at broker Bridgewell told Reuters: "Trafficmaster's new chief executive has taken over the company at a time when its most high-profile product is coming under pressure ... but his action plan is a step in the right direction."