The widow of Salvador Allende, the Socialist president who died in a 1973 coup, returned Saturday to a tumultuous welcome after 15 years of exile, issuing a call for hope and unity just days before a plebiscite on the continued rule of coup leader Gen. Augusto Pinochet.

"Today, my exile ends," said 74-year-old Hortensai Bussi, "an unjust and inhumane exile that I was subjected to for having always defended the democratic values of my country and the high values of the people of Chile: democracy, freedom and dignity."Hundreds of people shouted "Allende Lives" and "Out with Pinochet" as Bussi arrived at the capital's airport from Argentina. She returned with her oldest daughter, Carmen Paz Allende, and was met by another daughter, Isabel Allende, who returned Sept. 1 from exile.

Thousands more people gathered along the streets of a poor neighborhood waving pictures of Allende and signs saying "Welcome First Lady" as a caravan of some 1,000 vehicles made its way slowly to the center of the city. At some intersections, the crowd choked the street and limited traffic to one lane, pounding on cars and chanting.

"Our message is not fear but hope, not hate but joy," said Bussi in a statement at the airport, her voice choking with emotion at one point. "It isn't the past but the future we are constructing together."

Pinochet, 72, named the only candidate in the Oct. 5 plebiscite by the ruling junta, seeks a "yes" vote giving him eight more years as president. A "no" vote would be a call for an open election in about a year.

Reporters and photographers packed the airport reception area and some 500 people waited outside, singing the Chilean national anthem and chanting as Bussi walked out of the Customs area. The diminutive widow of South America's first democratically elected Socialist president was greeted by a line of leftist political leaders who she embraced and kissed.

Bussi left Chile with her family just four days after the coup in which her husband died. She has lived in Mexico since the coup. A third daughter, Beatriz, committed suicide in Cuba in 1977.

Bussi is the most famous of returning political figures who have taken advantage of Pinochet's lifting of forced exile put in place after the coup.

"She's the most clear connection to Allende's life," said Sergio Bitar, former minister of mining under Allende who was allowed to return from exile some four years ago.

He called her return "an important emotional link" for "recapturing the thread of history that's been distorted by the dictatorship."

Pinochet's campaign has taken advantage of the recent return of leftist leaders to boost its charge that his defeat would lead to a return to Allende's Marxist policies and the economic and political chaos it blames on his administration.

But Juan Somavia, a former ambassador to the Andean Pact of South American nations under Allende and former President Eduardo Frei, said at the airport the government had "crudely" handled its attempts to use the images of returning leftists in television commercials.