Roads in Northern Ireland and the Republic must be improved despite the challenges of Brexit, two major business groups said today.

The CBI and Ibec - CBI's equivalent in the Republic - said all-island development faced "significant risks" from the vote to leave the EU.

But in a report today, the groups insist that investment must be made to support exports, jobs and business development.

And the they vowed to identify all possible investment and funding opportunities to allow such investment to take place.

Northern Ireland received more than £170m towards business and infrastructure in the two years between 2013 and 2015 from the EU.

Projects part-funded by the EU include the £130m A8 road to Larne, which received €18m (£15m) from the EU towards its development.

Today's report said existing projects should be prioritised such as the A5 and A6 upgrades to Londonderry and the north west, as well as the M1/A1 Sprucefield bypass, which they said would improve the links between Dublin and Belfast.

CBI Northern Ireland director Nigel Smyth said: "Investment in all-island infrastructure and initiatives must progress with added urgency.

"Progress has been achieved over the last two decades but we must now set out ambitious plans to complete the connectivity across the island that businesses need.

"Ibec and the CBI will continue to identify and facilitate investment and funding mechanisms to deliver the ambitious proposal that is put forward by the all island investment project.

"Business will rise to the challenge and continue to build on the strong historical cooperative relationship across the island and between the two islands."

The report, entitled Connected: A prosperous island of 10 million people, argues for a comprehensive all-island motorway/dual carriageway network.

The report says better roads would make it easier for people to move and do business around the island - and overseas, by improving links to airports and ports.

And in the absence of most forms of EU funding for Northern Ireland, the report suggests financing options such as off-balance sheet financing from strategic investment funds, European Investment Bank (EIB) loans and European Commission funding via the Junker Fund.

Mary Rose Burke, director of corporate, strategic and international affairs at Ibec, said: "Infrastructure is the backbone of everyday life, underpinning economic activity.

"And if implemented, its report would improve everyday life and boost economic activity, investment and employment.

"Continuing to focus on delivering these needs is especially important given current uncertainties."