THE Port of Charleston and Maersk Line have negotiated a new five-year contract for container shipping services. Maersk Line, which began calling at Charleston in 1954, operates its Southeastern US load-centre at the port of Charleston's Wando Terminal. ''The Port of Charleston is extremely pleased to announce the continuation of our long-term relationship with this fine line,'' said Mr Don Welh, executive director of the South Carolina State Ports Authority. The combination of services between Maersk and the port of Charleston would continue to provide shippers with the calibre of cargo handling they deserved, he said. Maersk serves over 50 countries from Charleston. Maersk's parent company, A. P. Moller, is based in Copenhagen, Denmark, and operates a fleet of over 150 ships, including the 965-feet long container ships that call at Charleston.