The French High Commission in New Caledonia says it is expecting a decision from Paris tonight over whether to use police to free the port in Noumea.
The port has been in the hands of Kanak USTKE union members since last month.
The union is opposed to the arrival of multi-national shipping giants Maersk and MSC because they could dominate the freight market and force other shipping companies out of the port.
The High Commission says it held talks with USTKE for four days last week, but failed to find a solution.
According to new terrorism conventions, which France has signed, police and customs officials must be present at the port to guarantee security.
The port may risk a terrorism blacklisting if security conventions are not met.
Meanwhile, USTKE says it may call a general strike over the port dispute.