Eurostar faces the prospect of multiple compensation claims following a weekend of Channel Tunnel travel chaos.
The tunnel was closed for most of Saturday because of a lorry fire and shut again on Sunday morning after an unrelated electrical fault.
Only one of the two tunnels is fully open today (Monday) and Eurostar said its trains could be delayed by up to 30 minutes.
The Channel Tunnel is not likely to be fully operational until Tuesday.
Tunnel operator Eurotunnel said on its website it expected delays to its Le Shuttle trains of about 90 minutes at Folkestone. Trains from Calais would be operating to schedule.
About 12,000 passengers were affected when the tunnel was closed for most of Saturday, causing Eurostar to cancel 26 of its trains.
Eurotunnel said a load on a lorry on board one of its trains, en route from the UK to France, had been “smouldering” and triggered two CO2 detectors in one tunnel at 11.25am on Saturday.
Eurotunnel services had started running in the early hours of Sunday morning following the closure, after “residue smoke” was cleared from a tunnel.
Eurostar passenger trains resumed tunnel services again at about 11.30am on Sunday, but at a reduced speed as only the south tunnel was open.
However, there were further problems when the power supply fault meant the temporary closure again of the south tunnel.
Six Eurostar services from London St Pancras were cancelled on Sunday, as well as two from Paris and three from Brussels. Some passengers also faced long delays on services that did run.
Eurostar said it planned to run a full service from today and passengers were advised to check-in as normal.
Eurostar apologised to passengers after some took to Twitter to complain of long waits on the telephone booking system they were told to use.
“As Eurotunnel will not be completely operational Eurostar services may be subject to delays of up to about 30 minutes,” the company said.
“If you were scheduled to travel on Saturday or Sunday and wish to change your plans and were impacted by the tunnel closure, you can exchange your ticket free of charge, within the next 60 days to travel anytime within the next 120 days, or apply for a refund.”
Eurostar said it has a “generous compensation policy” in place for passengers affected by delays.