Christopher J. Rankin, the sharp-witted chief of P&O Nedlloyd in North America, will retire from that position in two weeks, the company disclosed this week.

Mike Seymour, a 27-year veteran of P&O Containers, will take over as North American president and chief executive of the world's third-largest container line when Mr. Rankin, 51, steps down on June 1.The appointment of Mr. Seymour, who was in charge of P&O Nedlloyd's South Asian and Far East divisions, underscores the carrier's strength in the Europe-Far East trade. Mr. Rankin's retirement comes just 18 months after the carrier was formed out of the merger of P&O Containers Ltd. and Nedlloyd Lines.

Mr. Rankin, a 24-year veteran of P&O Containers and, subsequently, P&O Nedlloyd, will retire so he can remain in the United States, rather than move to Britain to move up in the corporate hierarchy, said George Sopko, a P&O Nedlloyd spokesman.

''Basically, they're saying it's time for Chris Rankin to move up in the company. But the only opportunity would have been to go back to England. He declined because he wanted to stay in the States,'' Mr. Sopko said. Neither Mr. Rankin nor Mr. Seymour were available for comment.

Mr. Rankin joined P&O Containers Ltd. in 1974 and held various sales and marketing positions in London related to the Europe-Far East trade. He was appointed a director of the line in 1985. He was managing director for two years before being tapped in 1987 as chief executive of P&O Containers NA, the carrier's North American headquarters in East Rutherford, N.J.

During that time, he played an important role in trade's return to profitability for carriers following a brutal rate war in late 1980s and early 1990s. He was instrumental in the formation of the Trans-Atlantic Agreement, the predecessor of the Trans-Atlantic Conference, which reversed the rate decline by uniting traditional conference and independent lines under a single rate-setting umbrella. While he was often curt with reporters, he was known throughout the trade as an effective administrator and hard driving businessmen focused intensively on the bottom line.

Shipping executives doing business on the North Atlantic, where Mr. Rankin is best known because P&O entered the Pacific trades only recently, praised Mr. Rankin for his dedication to customer service.

''We have a monster contract with P&O, and whenever we experienced any kind of difficulty he was there, got on the phone and interceded to make sure his company functioned,'' said Alan Baer, president of Ocean World Lines, a major consolidator based in New York.

Mr. Rankin's departure is the latest of several top-level retirements, resignations and reshufflings in recent months at the U.S. units of major container lines.

Conrad Everhard retired as chief executive officer of Cho Yang (North America) Inc. Former APL Ltd. Chairman George Hayashi was recruited out of retirement to replace Kazuki Mori at the helm of Mitsui O.S.K. Lines (America) Inc. Ron Schley recently retired as the head of the U.S. unit of DSR-Senator Lines.