U.S.-Cuba relations, already strained by a custody dispute over a 6-year-old boy, grew more tense today when Cuba demanded the United States return the crew of a fishing boat it says was hijacked.

The Albacora allegedly was hijacked at knifepoint early Monday by Cubans desperate to reach the United States. Two crew members were wounded, according to the Cuban Foreign Ministry.

After Cuba alerted U.S. authorities, the Coast Guard seized the boat with eight people aboard. U.S. authorities said they had not yet decided what to do with the alleged hijackers.

Meanwhile, the State Department said immigration officials would seek to interview the father of Elian Gonzalez, the 6-year-old who was found Nov. 25 clinging to an inner tube off the Florida coast. His mother and stepfather died after a powerboat loaded with 14 people sank during an attempt to reach the United States. Elian, one of three survivors, is in the custody of relatives in Florida.

The Cuban government has charged that the U.S. failure to return Elian to his father in Cuba violates accords signed in 1994.

"U.S. authorities on one hand promise to prevent illegal immigration under the migration accords signed with our country," the Foreign Ministry said today. "On the other, they promote it with the stupid Cuban Adjustment Act, which automatically grants residence to any Cuban who arrives in U.S. territory."

The boy's father said Elian was taken out of the country without his knowledge.

The communist government has promised to hold mass street demonstrations in front of the U.S. interests section in Havana until the boy returns.

The State Department says Elian's fate should be decided by a Florida court. But the Cuban government says it does not trust the Florida courts to be impartial because of the state's large anti-Castro exile community.

"They can have all the demonstrations they want," said a State Department official. "In the United States we have laws we have to follow and uphold."