A number of large industries in the west and mid-west have said a reduction in the number of transatlantic flights through Shannon could trigger decisions to relocate elsewhere.
It is thought this is likely to happen when the Open Skies agreement between the EU and US comes into effect in 2008.
The companies' concerns are outlined in a new survey of industries in the region carried out by the employers' group, IBEC.
123 companies, which employ over 20,000 employees in total, were surveyed by IBEC.
25 of those companies expressed their strong concerns that a substantial reduction in flights from the US to Shannon could trigger decisions to relocate the company from Ireland.
The companies also expressed their fears that their corporate parents may stop any further investment if access to Shannon was hindered under Open Skies.
