The government is considering closing the Channel Tunnel at night in a bid to curb the number of migrants attempting to cross toward Britain, it has been reported.
According to the Daily Telegraph, the measure is being discussed by at emergency Cobra meetings as a "nuclear option" to resolve the crisis.
After months of disruption at Calais, the problems faced by authorities were again highlighted after a Sudanese man was alleged to have walked almost the entire length of the 31-mile tunnel trying to get to the UK.
After a journey said to involve dodging around 400 cameras and trains travelling at 100 miles per hour, he was arrested by British police close to the Folkestone exit in Kent on Tuesday evening.
At least nine people have died attempting to cross from Calais to the UK via the tunnel this summer, with a huge strain continuing to be placed on police and social services.
Sources said the option to close the tunnel - which is operated by Eurotunnel - had been considered, but added there were no immediate plans to do so.
A government spokesman said: "We have and continue to consider all potential courses of action to improve security at the Channel Tunnel in Coquelles and to prevent any loss of life.
"A number of new security measures have been introduced and Ministers both here and in France keep the situation under constant review."
However, Labour said closing the tunnel would be "very damaging" to business and tourism and would be "a clear sign of the failure of David Cameron's approach to tackling the challenges at Calais".
Shadow Immigration Minister David Hanson also claimed that the government have "no real grip" on the situation despite "clear warnings" from businesses and MPs over previous months.