SAN JUAN, Puerto Rico (AP) _ A Teamsters Union member and two former union leaders were arrested and charged with murder in connection with the Dupont Plaza Hotel fire that killed nearly 100 people in 1986.

Another man, Hector Escudero Aponte, 36, who admitted to setting the blaze, was allowed to plead guilty to lesser charges in exchange for testifying against the three, said San Juan District Attorney Ismael Betancourt.

Escudero Aponte made the deal with prosecutors just before he was to go on trial Wednesday on 97 charges of first-degree murder and one charge each of arson and conspiracy.

Instead, he pleaded guilty to charges of second-degree murder, arson and conspiracy and was sentenced to concurrent terms totaling 30 years.

The union denied Wednesday its leadership had been involved in the fire, which came during a labor dispute at the hotel.

''I have always said no official of the Teamsters has participated in this,'' Secretary-Treasurer Jose E. Cadiz told a news conference. ''This union is innocent of what happened at the Dupont Plaza.''

The fire on New Year's Eve 1986 at the beachfront Dupont Plaza killed 97 people and injured more than 140 others.

It was the second-deadliest fire in U.S. history. The worst blaze was in 1946 at the Winecoff Hotel in Atlanta, which left 119 people dead.

Puerto Rico's Justice Department identified the three men arrested Wednesday as Manuel de Jesus Santiago Rios, vice president of Teamsters Local 901 at the time of the fire and on leave from his job as a waiter; Luis M. Muniz Marquez, former union steward and butcher at the Dupont Plaza, and Luis Elias Vega Rios, a former utility employee.

Each was charged with 97 counts of first-degree murder and one count each of arson, conspiracy and damage. De Jesus Santiago Rios and Muniz Marquez were also charged with one count of perjury.

Betancourt told the court the three helped ''instigate'' the fire but gave no details. He said the fire might not have taken place without their ''intellectual presence.''