UK officials mull Scotland-Northern Ireland 'Boris bridge'
Boris Johnson

Prime Minister Boris Johnson has ordered officials to look into building a bridge between mainland Britain and Northern Ireland, his spokesman said Monday.

The idea of a bridge from Scotland to the province of Northern Ireland has been around for years but has gained new impetus under Johnson's leadership.

It has support from some pro-British politicians in Northern Ireland as a way of boosting connections with the mainland, which are being strained by Brexit.

But others question the feasibility and cost of the project given the deep water and windy conditions in the North Channel, which at its narrowest is 12 miles (19 kilometres) across.

Experts say a much longer bridge would be required.

In 2007, the Centre for Cross Border Studies think tank put the cost of such a project at £3.5 billion (4.1 billion euros). But experts have said the price tag could now be at least £15 billion-20 billion.

Another issue is how to navigate the large quantities of surplus munitions dumped on the sea bed between Scotland and Northern Ireland after World War II.

"Work is under way looking into the idea of the bridge," Johnson's spokesman said.

He said that government officials had been tasked to look into the details and report back to Downing Street, although emphasized that the work was at an early stage.

Johnson is known for his fondness for big infrastructure projects -- although they do not always end well.

As London mayor, he pushed for a new "garden bridge" over the River Thames, which was scrapped after costing £53.5 million (63 million euros, $69 million).

Asked about his record, Johnson's spokesman said: "The prime minister is ambitious in terms of infrastructure projects.

"He is looking at a wide range of schemes across the United Kingdom which could boost connectivity."

In December, Ian Paisley of Northern Ireland's Democratic Unionist Party (DUP) called on Johnson to "build a Boris bridge".

The DUP is concerned that changes to Northern Ireland's trading arrangements under the terms of Britain's exit from the European Union could weaken ties between the province and the mainland.

"It is a very interesting idea," Johnson replied in the House of Commons debate.

"I advise him to watch this space and, indeed, to watch the space between the islands."

However, others are sceptical.

Northern Ireland's Ulster Unionist Party has previously warned that there were many roads, schools and hospitals that needed funding first before embarking on such "fantasy projects".