The old guard leaders of the National Marine Engineers Beneficial Association said a recent court decision proves that they are the legal representatives of the country's shipboard engineers.

The decision "makes it clear to all, that any meetings, elections, conventions, or resolutions passed by the various dissident groups are illegal," said Alexander C. Cullison, the president of one faction of National MEBA, in a statement released Monday.He was referring to a February ruling by a U.S. appeals court here that the Department of Labor properly dismissed a complaint filed by a MEBA member against a 1990 election for delegates to a National MEBA convention.

But Mr. Cullison's claim was ridiculed by Gordon M. Ward, president of the alternative National MEBA organized last week.

"This is a leap of faith, to say the least," he said. "The case has nothing to do with the events we're contesting. Our position is that we are the National MEBA."

Last week, Mr. Ward's union - District No. 1-Pacific Coast District, MEBA - joined forces with MEBA's District No. 2 to form a second National MEBA.

Together, the two unions represent some 9,000 shipboard engineers who work on U.S.-flag containerships and tankers and the Military Sealift Command. District No. 2 is headed by Raymond T. McKay.

Their action leaves Mr. Cullison in charge of a MEBA with only a handful of engineers. The majority of his faction of National MEBA come from the National Maritime Union, which represents unlicensed seamen, and two divisions representing workers at U.S. military bases and federal aviation agencies.

Mr. Cullison's statements come one week before the votes are counted on a membership referendum that his group says will convince the AFL-CIO and other maritime unions that they have the support of the engineers.

Lane Kirkland, president of the AFL-CIO, has met with both Mr. Cullison and Mr. Ward and "agreed to look into the situation" within MEBA, a spokesman for Mr. Kirkland said.

The decision by the U.S. Court of Appeals for the District of Colombia Circuit was made on procedural grounds. It affirmed arguments made by former Secretary of Labor Elizabeth Dole that the convention delegates were not union ''officers" subject to federal union election laws.

Ms. Dole also had ruled that Mr. Petersen had not exhausted internal union remedies.

The court said nothing about the legitimacy of National MEBA or the dispute within the union, however.

But the decision "sends a signal that illegal dissident actions are beyond the law and will not be tolerated by the courts," Mr. Cullison said.

"That's legally preposterous," said David J. Bartone, the attorney who brought the complaint. "They're trying to bootstrap onto something with no relevance to the case."

Mr. Bartone said he will file for a rehearing so the court can decide whether a convention delegate constitutes an official under U.S. labor law.

In an interview Monday, Mr. Cullison derided the alternative National MEBA, which he said was now under the control of Mr. McKay and in the "financial death grip" of the Seafarers International Union, which recently lent the Ward group $500,000 for operating expenses.

"There is no validity whatsoever to this group," Mr. Cullison said. "We have the charter (for National MEBA) from the AFL-CIO."

He said Mr. McKay "hasn't withdrawn or broken off" from his group.

"We had a majority of the elected delegates (from the engineers) at our convention," Mr. Ward countered. He said the new national executive committee had 15 seats, seven from the Ward group, six from District No. 2 and two from District No. 3, the radio officers union.

"They can't dictate to us, and we can't dictate to them," he said of District No. 2.

Mr. McKay was not available for comment Tuesday. But a spokesman said: "It should have been plain to him (Cullison) that because District No. 2 went with Ward, obviously Ward is the legitimate representative of the engineers."

At last week's convention, Mr. McKay said he was strongly opposed to Mr. Cullison and his allies.

"We will fight them like they've never seen a fight before," he promised the Ward forces.