Knud Erik Moeller Nielsen, a rising star at A.P. Moller-Maersk who was slated to become chief executive of Maersk Line, died Thursday morning during a meeting at the company's Copenhagen headquarters. He was 51.

Mr. Moeller Nielsen, executive vice president of Maersk's liner division in Copenhagen, was widely respected in the container shipping industry. His death has elicited heartfelt comments from top figures in the industry.''He was enormously respected within the industry as a hard negotiator who knew his business, and also as a straight dealer you knew you could trust,'' said Christopher Rankin, president and chief executive of P&O Nedlloyd North America.

Others agreed.

''Erik was one of the icons of our industry. He was a very hard-working guy, and always stood by his word. If he promised something, he would make damn sure he and his company would deliver,'' said Olav Rakkenes, chairman and chief executive of Atlantic Container Line. ''He was a fantastic guy and a good friend.''

Analysts speaking on condition of anonymity said Maersk Line is a strong company and is likely to weather Mr. Nielsen's death without severe disruption to its operations or direction.

Maersk is arguably the world's largest container shipping line, last year growing more than 21.7 percent, more than three times the growth of world container trade.

The Danish carrier, part of the much larger A.P. Moller shipping and shipbuilding group, is aggressively expanding into new markets on the strength of its solid reputation with shippers.

Mr. Nielsen, who was Danish, spent his entire career at Maersk, including positions abroad as manager of the company's container department in Japan and as an executive of Maersk Inc. in the United States.

''His sudden death was a great shock to all of us, and he will be greatly missed,'' said Ib Kruse, chief executive of Maersk Line and a partner of A.P Moller. ''Our sympathies go out to his family.''

''There's a lot of shock in the organization,'' Phil Connors, executive vice president at Maersk Inc., said from the company's U.S. headquarters in Madison, N.J.

Other executives weighed in with comments about an industry colleague many have known for years.

''Erik was a dear friend both personally and professionally for most of my career,'' said John Clancey, president and chief executive of Sea-Land Service Inc. ''Our industry and international commerce loses both a visionary and one of the most knowledgeable and talented people in the industry.''

''Erik Moeller Nielsen was widely respected for his honesty of character and expertise in the transportation industry,'' said John Pachtner, a spokesman for American President Lines. ''APL mourns his passing and deeply sympathizes with those close to him professionally and personally who are now grieving over this tremendous and sudden loss.''