Hundreds of passengers were stranded for hours on five Eurostar high-speed trains after reports that migrants were blocking the tracks leading to the tunnel under the English Channel and were attempting to climb aboard. According to the Eurostar Twitter feed, three of the trains then went on to London early on 2 September, while two others returned to their original departure stations in London and Paris.

Eurostar had announced on Twitter on 1 September, that it was holding its trains "whilst authorities deal with trespassers" and then said the trespassers had been spotted on the tracks at the station in Calais. The trains stayed in place as the trespassers were removed from the tunnel and away from the tracks, it said.

"We waited at the entrance of the tunnel, because they told us there were people in the tunnel, and we waited for - I think - two hours-and-a-half, or maybe three hours and in the end, without giving us any information, they said we would go back. So probably the people got stuck but they didn't manage to get them out. So, we had to wait, and they decided to go back to London," said one passenger on return to London's St Pancras station.

Local media reported the trespassers were migrants attempting to cross into the UK through the Eurotunnel. So far in 2015, thousands of refugees have attempted to make the dangerous crossing.

"They told us there were some people in the tunnel. They didn't tell us exactly what the situation was about. I am guessing it had to do with the migrants that were trying to get through and cross onto the other side. They told us that the police was there, but that is basically it," said another passenger, who added he was too frustrated and tired to seek compensation from Eurostar.

People on the roof

Passengers on one of the London-bound trains, which stopped less than a mile from the tunnel, were told at one point to be very quiet and listen for the sound of people climbing on the roof. A helicopter with a searchlight then circled the train as guards walked the tracks looking for migrants, but seemingly none were spotted.

With the power out, passengers on that train sat in the dark for nearly four hours. The heat and mugginess in the cars rose as conductors walked the aisles with wind-up torches. A woman in business class wept and many passengers said they could not breathe in the stifling air. For many of those passengers who expected to be waking up in Paris on 2 September, they find themselves stranded in London with nowhere to stay.

"There is a whole crowd of people out there with nowhere to stay tonight. We were expecting to be in Paris this evening. They are saying they haven't got hotels for them, so that is an issue," said one passenger, who was fortunate enough to live in London and therefore return home.

However, there were others who are left in London with nowhere to stay who are angry with Eurostar's handling of the crisis. "This is totally unacceptable," said one French passenger. "So, we have been actually waiting three-and-a-half hours in front of the tunnel, because some migrants were supposed to cross the tunnel. The police, the French police, were sent there for about three hours, to try to chase them, but they didn't manage for some reason.

"Even though I am French and I thought they could do it in three hours but no they couldn't, so the train could not go through. So, after three-and-a-half hours they told us we can't go further, we take you back to London, and we wish you a very good night. That is all they said."

Eurostar has offered to exchange tickets to passengers affected by the suspended service.