Boris Johnson today delivered a fresh hint that he wants to press ahead with building a bridge between Northern Ireland and the British mainland.

The Prime Minister previously raised the idea of the huge infrastructure project, saying it would show the commitment to keeping the Union together after Brexit.

However, engineers are deeply sceptical over whether it would be feasible to build such a transport link.

They have pointed out that the depth of the water and abandoned munitions in the area where the bridge would likely be placed would make it incredibly complex and astronomically expensive.

Boris Johnson, pictured in the House of Commons this afternoon, has signalled his support for a bridge to be built between Northern Ireland and Scotland

But asked by the DUP's Ian Paisley today during the debate on the Queen's Speech in the House of Commons about building a 'Boris bridge', Mr Johnson suggested he was in favour of the idea.

He told the Northern Irish MP: 'It is a very interesting idea. I advise him to watch this space, and indeed watch that space between those islands.

'What you have said has not fallen on deaf ears.'

Mr Johnson apparently told officials in September this year to look at the viability of building such a bridge between Northern Ireland and Scotland.

Staff at the Treasury and Department for Transport (DfT) were ordered to advise on the costs and risks of such a project.

The idea was originally put forward by Mr Johnson last year, when he was foreign secretary.

The suggested route of the bridge would see a 28 mile link between Larne in Ulster and Portpatrick in Scotland.

Documents revealed that the PM wanted to know where money for the new scheme could come from and the risks which appear to include 'WW2 munitions in the Irish Sea'.

The DfT produced a paper on the subject after talks between the DUP and former transport secretary Chris Grayling.

A spokesman for the government told Channel 4 News: 'This PM has made no secret of his support for infrastructure projects that... [could] strengthen the Union.'

A bridge between Northern Ireland and Scotland has previously been floated by Mr Johnson and the DUP. The suggestion was to link the 28 miles between Larne in Ulster and Portpatrick in Scotland, pictured on a map

They added: 'Government regularly commissions work to examine the feasibility of projects.

'During the leadership campaign candidates spoke about a number of issues which resulted in Number 10 commissions ahead of a new Prime Minister taking over.'

Mr Johnson has previously been linked to unsuccessful infrastructure projects such as the Garden Bridge which was planned for London.

In 2011 the Prime Minister, who was then Mayor, also backed plans for a Thames Estuary airport. This idea was nicknamed 'Boris Island'.