HAVANA — Cuba announced Tuesday that its economy shrank this year for the first time in nearly a quarter century as a plunge in aid from Venezuela overwhelmed a surge in tourism set off by detente with the United States.

Economy Minister Ricardo Cabrisas and President Raul Castro told Parliament that the island’s gross domestic product fell nearly 1 percent after seeing average annual growth rate of nearly 3 percent in 2011-2015.

Cabrisas blamed the slump on Venezuela’s troubles and a decrease in revenue from Cuba’s few exports, which include sugar, refined gasoline and nickel, whose price has dropped in recent years.

“In spite of the drop in GDP, the free social services that our population enjoys have been preserved, defying predictions that the Cuban economy would collapse and upsetting blackouts would return,” Castro said.

The two men spoke to Cuba’s rubber-stamp National Assembly, which also passed a law announced by Castro last month banning public memorials to his brother Fidel, the revolutionary leader who died on Nov. 25 at age 90.

The last time official figures showed a fall in Cuba’s gross domestic product was in 1993 after the Soviet Union collapsed, abruptly stripping away much of the island’s aid and trade.

A global drop in petroleum prices has slammed Venezuela’s oil-dependent economy, forcing it to reduce shipments of heavily subsidized crude oil to Cuba.

In addition, the number of contracts for Cuban professional services with Venezuela has dwindled and some payments have not been made. Many Cuban doctors have long traveled to Venezuela, with their salaries going to Cuba’s government.

“This confirms what we had said about Venezuela’s situation leading to a recession,” Cuban economist Pavel Vidal, a professor at a university in Colombia, told The Associated Press.