France will investigate a break-down of Eurostar trains that trapped about 2,500 passengers in the Anglo-French Channel Tunnel on Friday night, as bad weather could not be the sole cause, the transport minister said. Eurostar, which is owned by the French and Belgian state railway operators and the UK, has said the trains were stranded after moving from cold air outside into the warmer tunnel caused problems with condensation. "The transport ministry will start an inquiry to find out what happened, I"ve just talked to the Prime Minister about it," Transport Minister Dominique Bussereau said on Monday during a visit to China with Prime Minister Francois Fillon. "We can"t believe that Eurostar trains can"t run for three days because of snow, so there must be a technical problem," he was quoted as saying by Reuters. Eurostar has suspended its passenger train services through Monday while trains are modified to cope with more snow expected in northern France. Passengers were stuck on the trains for up to 16 hours in the night from Friday to Saturday. Eurostar said on Sunday it needed to modify the snow screens and snow shields in the trains" locomotives. Eurostar carries about 40,000 people a day between England and continental Europe. The suspension of its services, coupled with problems with cross-Channel ferries and bad weather, has snarled traffic in southeastern England.