Eurostar suffered cancellations and delays on Monday after a person was hit by a train and killed on the English side of the cross-Channel service.
"Due to a person hit by a train between Ashford International and Ebbsfleet International, the High Speed Line is currently closed," Eurostar, which offers passenger rail services between London, Brussels and Paris, said in a statement.
Emergency services were at the scene in southeast England and were set to advise on when the vital transport link could be reopened.
A British Transport Police (BTP) spokeswoman said they were called to the line at 1142 GMT on Monday following a report that a person had been hit by a train.
The death is not being treated as suspicious.
Some 400 trains and 1.5 million lorries pass through the tunnel every day.
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