Workers on the world famous Channel Tunnel have been taken to hospital after suffering from carbon monoxide poisoning.
According to French officials, some 60 workers were working overnight on the tunnel changing rail tracks on the line between Calais and Folkestone.
"Detectors in the tunnel didn't show excess levels of carbon monoxide," John Keefe, director of public affairs at Eurotunnel Group, told Kent Online.
"A number of workers were taken to hospital for medical observation as a precaution and Eurotunnel is monitoring their condition carefully."
A welder was taken ill in the early hours of Sunday and carbon monoxide poisoning was later diagnosed.
Eighteen other workers were also taken ill but Eurostar services were reportedly unaffected.
The affected employees were sent to local French hospitals to be treated, but a French official stressed their condition was not a cause for concern.
An investigation has been launched.