Shutting down Eurotunnel services overnight to stem the migrant crisis will damage the UK economy.

That is the message from the Channel Tunnel operator who says it will sue the government for £200m if it implements such a plan.

According to reports in the Telegraph and the Times, company president Jacques Gounon has written to Christopher Irwin, the head of the UK delegation to the Channel Tunnel Intergovernmental Commission, threatening to seek compensation.

He said: "Under the concession agreement Eurotunnel would be obliged to claim for losses which we estimate could easily attain the level of circa £200m per year.

"Any significant reduction in overnight services through the Channel Tunnel would have a grave impact not only on the concession holder but also on the UK economy.

"We believe it would be far better for resources to be focused on resolving the 'Calais crisis' rather than sowing panic among customers and investors and, ultimately, damaging the economy."

The news comes as it was revealed around 30 migrants gained access to the Eurotunnel terminal in Calais by guessing the code for a secure gate.