Plans for a £15billion bridge between mainland Britain and Northern Ireland are being backed by Boris Johnson, The Telegraph can disclose.

The Foreign Secretary said that a mooted 24-mile link across the Irish Sea which has already been backed by the Democratic Unionist Party should be looked at “seriously” by the Government.

It comes after Mr Johnson said he wanted to see a bridge across the English Channel in February to unite France and England.

A source close to Mr Johnson told The Telegraph: “Boris thinks this is an interesting idea which should be looked at more seriously - as politicians in both Scotland and Northern Ireland have already said.

“It's the kind of ambitious project we need to make a success of Global Britain.”

Mr Johnson on Monday retweeted an article for the Reaction website which set out the positive case for the bridge by former Telegraph journalist George Trefgarne.