A strike that might have begun as early as this weekend at 14 ports on the East and Gulf Coasts has been averted for 30 days while negotiations continue.

The union representing 14,500 dockworkers, including in Philadelphia, and management for shipping lines and port employers agreed to extend their contract talks until late January, a federal mediator announced Friday.

The International Longshoremen's Association (ILA) had been preparing for a possible strike at 12:01 a.m. Sunday, affecting ports between Maine and Texas. The bargaining is for a final master contract governing containerized cargoes, which are commodities shipped in 20- or 40-foot containers.

Ports on the Delaware River would not be as severely disrupted as some ports such as New York because more cargoes arrive here in bulk quantities, and in smaller crates, and on pallets, including plywood, steel, paper, cocoa beans, and fruit.

Longshoremen who handle cargoes not shipped in containers would stay on the job.

The primary issue between the ILA and the U.S. Maritime Alliance is "container royalties," payments made to longshoremen based on the weight of containerized cargo. Management wants to cap those payments.

The National Retail Federation applauded the contract extension but urged "both parties to remain at the negotiating table."

A Maine-to-Texas longshoremen's strike, called a coast-wide strike, would disrupt retailers' shipments of spring and summer merchandise, such as Easter shoes, home goods, swimwear and patio furniture, and affect manufacturers, wholesalers, truck drivers and farmers, the trade group said.

Contact staff writer Linda Loyd at 215-854-2831 or lloyd@phillynews.com.