A ship carrying 40,000t of rock salt from Maine to New Jersey is being prevented from completing its order, as it does not fly an American flag.

New Jersey is already facing a shortage of rock salt due to heavy snowstorms this winter.

The ship will be permitted to unload in New Jersey, if the federal government issues a waiver under the 1920 Merchant Marine Act.

If a waiver is not provided, the rock salt will have to be transfered to slow-moving barges in order to reach New Jersey, reported NorthJersey.com.

The nearest available ship that complies with the regulation would take around a month to arrive in the area.

Meanwhile, US senators Cory Booker and Bob Menendez told NorthJersey.com that their offices have contacted the Homeland Security and Transportation departments to find a solution.

American Maritime Partnership chairman Thomas A. Allegretti was quoted by nj.com as saying: "The maritime industry is working to ensure that the state has the resources it needs to meet its seasonal demand."

"Despite short notice by transportation officials, maritime operators are moving to accelerate a request for additional salt and will deliver a new shipment to New Jersey before it is needed again."