A warning of further disruption to Channel Tunnel services because of power problems has come from operator Eurotunnel.
Shuttle services were delayed by up to five hours on Wednesday. Eurostar passengers were also held up by about an hour.
The problems come just days after thousands of passengers were left stranded by a lorry fire on a train in the tunnel on Saturday.
Power supply issues then led to the cancellation of 11 trains on Sunday.
Earlier on Wednesday a Eurotunnel spokesman said: “As we were conducting the re-establishment of services early this morning, we encountered a power supply line issue.
“Our maintenance teams have gone out to inspect this. The tunnel is open but we are running a reduced service in the meantime.”
Eurotunnel spokesman John Keefe told the BBC: “They [the tunnels] will be fully operational when everything is safe to re-open.
“At the moment we’re not putting a time to that. It will be some time this week but we’ve got to wait and see how long it takes.”
When he was asked whether that meant at least two more days of delays, he added: “I think that would be safe to say.
“We are looking to make sure this is done once and done properly so that we get back to full safe operations.”
The latest update on the Eurotunnel website yesterday said: “Following the tunnel incident on Saturday, we are operating our service with four of the six sections of the tunnel available; this means that a reduced timetable is in place with one passenger departure in each direction every two hours.”
The tunnel will also be closed overnight on Saturday due to planned maintenance work with all services suspended.
The last departure from the UK on Saturday night will be at 9.20pm and 10.20pm from France. Services are due to resume at 6.20am on Sunday from the UK and 7.20am from France.