Travellers attempting to cross the Channel today are being warned of delays of up to two hours due to a problem being investigated.

Schedules are being disrupted because one of the rail lines is out of operation - though the reason has not been specified.

Services to and from France on both Eurostar and Eurotunnel are both affected. Half-hour queues earlier this morning have quickly risen to two-hour delays, though some passengers were already reporting hold-ups of three hours.

The car shuttle runs from Folkestone via Eurotunnel and passenger services from Ashford, Ebbsfleet and St Pancras for foot passengers on Eurostar trains.

Police have confirmed they are not involved in any incident, but Eurotunnel has yet to provide details of the problem.

Tickets to non-reserved Eurotunnel customers were being suspended, so anyone turning up without a prior booking would not be allowed to board.

Eurotunnel apologised for the inconvenience in a statement posted on its website, explaining it was operating with some timetable disruption due to an 'incident' in the tunnel which was in the process of being resolved.

"We sincerely apologise for the inconvenience this will cause to your journey," the statement added.