An upgrade of part of the Belfast to Londonderry road should be taken forward urgently following the delay to the dual carriageway in Co Tyrone, the CBI in Northern Ireland said.
Improving the stretch between Castledawson and the motorway at Randalstown in Mid Ulster is among major alternative schemes under consideration by the Executive.
Ministers are deciding what to do with millions of pounds earmarked for the development of the route between Derry and Aughnacloy, in Co Tyrone, which was stalled by a recent High Court decision.
CBI chairman Ian Coulter said: "It is now vitally important that the Executive reconsiders how to best spend the capital monies available on infrastructure projects of the highest economic value, as soon as possible."
He said several major schemes were in stages of advanced preparation.
"We are strongly of the view that one such scheme, the A6 Randalstown to Castledawson, must be taken forward by the Executive as a matter of urgency," he added.
"This investment will bring significant economic benefit and increase the connectivity between our two major cities."
Other forms of infrastructure spending are also being considered by the Executive since public money earmarked for the Londonderry to Aughnacloy project will not be spent on schedule because of the delay.
In September it was revealed around £10 million a month set aside for the new A5 road will have to be returned to Stormont for as long as delays to the project continue. The CBI said the £330 million dualling of the road from Derry to Aughnacloy, which forms part of a proposed key cross-border business route linking Dublin and the north west, should be pursued quickly.
Regional development minister Danny Kennedy has said his officials were carrying out fresh assessments after a recent legal challenge to the development's impact on wildlife habitat by farmers and landowners was successful.