COST could rule out running Eurostar trains for high-speed domestic services from 2007.

GNER chief executive Christopher Garnett said it was too early to make any commitment to operate the trains if his company won the Kent franchise.

The former Kent resident said the idea, strongly backed by Kent County Council, may not be financially viable.

Although new Hitachi bullet trains are on order, they will not be ready until 2009 at the earliest.

KCC chiefs insist that for symbolic purposes at least domestic services between Kent and St Pancras must be in place when the £5.4bn Channel Tunnel Rail Link opens fully in 2007.

But Mr Garnett declined to give any assurances. He said: "I am very aware, having lived in Kent for many years, of the frustration in Kent of having been promised this thing for so long, to see the line open and not to be able to use it. It is going to be pretty upsetting.

"We are aware of the pressures. We've got to sort out what we can do about it. If it adds to costs, you could lose the bid because the name of the game is the lowest price wins."

There was still uncertainty over the price premium charged to passengers using high-speed domestic services into St Pancras.

"That is what makes this one of the most complicated bids to do," he said.