The owners of Newport docks, which supports 3,000 local jobs, say they are concerned about its future because of plans to build a new M4 relief road south of the city.
Associated British Ports says the route could impact on its existing operations and "future development of the Port of Newport."
Newport is Wales’ leading general cargo port, handling in excess of 1.5m tonnes of cargo per year. Its operator, ABP, is repeating its concerns over the Port’s future on the day that Assembly Members prepare for a debate in the Senedd on the wider importance of ports to the Welsh economy.
ABP says the route would mean building a bridge which would bisect the North and South Docks, creating a height restrictions and a report found that 58% of vessels entering the North Dock during 2004-2008 would not have been able to access it if the proposed bridge had been in place.
ABP says the plans are "a real threat" to the future of Newport docks.
ABP has proposed an alternative crossing point several hundred metres further north of the current proposal, but says this has not been accepted by the Welsh Government.