French officials say nineteen workers have suffered carbon monoxide poisoning while working overnight in the Channel Tunnel, with one of them in a serious condition.
The incident happened as some 60 workers were changing rail tracks on the line between Calais, France, and Folkestone.
A welder was taken ill in the early hours of Sunday and carbon monoxide poisoning was later diagnosed.
Tunnel traffic was unaffected.
Eighteen other workers have also been taken ill.
An investigation has been launched into the cause of the incident.
More top news
London was in a celebratory mood on 7 July 2005, but everything changed when three suicide bombers attacked the capital's transport network.
A car dealer who called an amputee soldier a '******* cripple' and threatened to have him beaten up has been jailed.
People travelling into the capital have been getting off a stop early to walk together in remembrance of the victims of the 7/7 bombings.