Eurostar has suspended services between London and Paris for the rest of Friday after the discovery of an unexploded Second World War bomb near tracks in the French capital.
Thousands of passengers face travel disruption as the cross-Channel operator was scheduled to run 32 trains in either direction throughout the day.
A large crowd of people who were booked on affected services has gathered outside the check-in area at London St Pancras station.
Eurostar said in a statement: “Due to the discovery last night of an unexploded bomb from the Second World War during work carried out on the tracks in St Denis (north of Paris), traffic has been completely halted to and from Gare du Nord.
“As a result, all Eurostar trains are cancelled to and from Paris today.”