Torching tires and blocking traffic, the French workers were protesting expected job cuts in the French port city of Calais linked to Eurotunnel's sale of its ferry service. Both freight and Eurostar passenger trains suspended service until further notice.
The Eurostar train service carries about 10 million people a year across the English Channel, with summer marking the height of tourist season.
An Associated Press photographer saw the striking workers swarm the tracks this afternoon. It was the second time in a week port workers have paralyzed the train lines.