Eurostar has told passengers to expect "major" disruption to trains this weekend while an unexploded World War Two bomb is deactivated.
The bomb was discovered near Gare du Nord in Paris, and has led to the cancellation of five services between the French capital and London on Sunday.
Of these, four were from Paris, while the other was from London. Meanwhile, another service from London has been diverted, with many more expected to be delayed.
With major disruption expected, passengers who were due to travel this weekend have been urged to change their plans.
Free exchanges and refunds have been offered by Eurostar for anyone travelling on Saturday or Sunday.
The unexploded bomb was discovered during engineering work in the area north of Gare du Nord, a railway station served by Eurostar.
Roads and domestic train services in Paris will also be disrupted while the operation to make the device safe is carried out.
Eurostar said: “As a result of this operation we have had to substantially revise our plan for Sunday and will be running a modified timetable.
"This includes the cancellation of five services and the rerouting of one service to Marne-la-Vallée."
Residential areas close to where the bomb was found will be evacuated.
Eurostar added: "We are sorry for the impact this will have on our customers and would strongly advise anyone scheduled to travel with us between London and Paris this weekend to consider changing their plans."
