The North Carolina State Ports Authority has cited safety concerns in the delay to reopen the port of Morehead City, shut down on Wednesday after a chemical spill in the harbour.

In a statement issued last night (HK time), NC Ports said "utmost safety procedures are [being] exercised in the remediation of a hazardous materials incident".

Officials said the chemical PETN, or pentaerythritol tetranitrate, was spilled early yesterday morning during a vessel operation at the Port terminal.

PETN is described as the primary ingredient in detonating cords used for industrial explosions and also used in military devices and blasting caps.

Officials said the chemical, itself, is not a threat. It is only when mixed with other chemicals that it can become explosive.

"The Ports Authority's goal is to reopen the port of Morehead City as safely and as quickly as possible," said CEO Thomas Eagar.

The port terminal was closed as Carteret County first responders and emergency management officials responded to the spill. No reported injuries or environmental damage has been reported.

Highway 70 from 4th Street to Beaufort was closed and officials also requested a voluntary evacuation by those in areas surrounding the port.

The accident occurred during discharge of a commercial ship at the port. The port authority said vessel operations at North Carolina Ports were handled by private stevedoring companies and no NC State Ports Authority employees were involved.

Hazardous materials are among the top imports at Morehead City and are handled routinely under all prescribed regulations for safe handling and transportation and in conjunction with local and state emergency management agencies.

"We are grateful to all the first responders and emergency management personnel for their quick response and the safe manner in which the incident was handled," said Eagar.