MEXICO CITY — During the economic turmoil of the early 1990s, power cuts in Havana were so routine that residents called the few hours of daily electricity “lightouts.”

Now, grim economic forecasts; the crisis in its patron, Venezuela; and government warnings to save energy have stoked fears among Cubans of a return to the days when they used oil lamps to light their living rooms and walked or bicycled miles to work because there was no gasoline.

Addressing members of Parliament last week, Cuba’s economy minister, Marino Murillo, said the country would have to cut fuel consumption by nearly a third during the second half of the year and reduce state investments and imports. His comments, to a closed session, were published on Saturday by the state news media.

Cuba’s economy grew by just 1 percent in the first half of the year, compared with 4 percent last year, as export income and fuel supply to the island dropped, said Mr. Murillo.