Eurostar has cancelled services through the Channel Tunnel because of a power failure.
The disruption has affected customers catching passenger trains from London St Pancras, and also those using the Eurotunnel, which operates freight and car services.
The issue began at around 2pm and is not expected to be resolved until later this evening.
A Eurostar spokesman said: ‘We’re sorry for the current delays.
‘We’ve held traffic due to a technical issue on the line. Updates to follow.’
Eurotunnel added: ‘Our passenger service is temporarily suspended due to a technical fault in the tunnel which is in the process of being resolved.
‘We sincerely apologise for the inconvenience this will cause to your journey.’
The suspension has already caused tailbacks at Junction 11a on the M20 at Folkestone.