A Cuban official who had been viewed as a possible successor to President Fidel Castro was fired and blamed for an energy crisis on the island.

BY NANCY SAN MARTIN

WASHINGTON - A prominent Havana official, who was viewed as a possible successor to Cuban leader Fidel Castro, was removed from his ministerial post for what the government called inefficiencies that led to a crippling energy crisis.

But observers said Marcos Portal León's dismissal as minister of basic industries Thursday was more likely intended to bury any notion that a replacement for Castro exists while also providing a scapegoat for an electricity shortfall. Cubans now endure daily hours-long power outages.

''He must have heard himself mentioned as a possible successor, started to act as though it was a done deal, and blew it,'' said Jorge Domínguez, a Harvard University Cuba expert. ``His dismissal is a pretty big deal. This guy was really a very effective minister who had also risen politically.''

Adding to the drama is Portal's personal ties to the Castro family. He is married to the niece of Castro's younger brother Raúl, the designated successor.

''He was a protégé to Raúl,'' said Jaime Suchlicki, director of the University of Miami's Institute for Cuban and Cuban-American Studies. ``This demonstrates Fidel's power and another move toward more centralization of power.''

The government statement lambasted Portal for ''strong tendencies toward self-sufficiency and underestimating the opinions of other experienced colleagues'' and for ``not being capable . . . of warning the top leaders of the [Communist] Party and the State about the risks of an entirely preventable [energy] crisis.''

Portal, 59, was named minister in 1983. The announcement did not indicate if he would still serve in the government. Efforts to reach Cuban officials in Washington were unsuccessful.

Portal will be replaced by Yadira García Vera, a Communist Party leader with a chemical engineering degree.