"We urge the government to stop crying and start working," Democratic Unity coalition leader Jesus Torrealba told a news conference under a sign reading: "Thank you Venezuela, we won!"

The government boosted imports in the run-up to the election, but overall shipments have tumbled this year because of a recession and low oil prices, with many economists warning the scarcity may worsen over Christmas.

"We're just a few weeks away from a very serious problem in terms of food," Torrealba said.

Anger over shortages propelled the opposition to a long-elusive victory in Sunday's vote for a new National Assembly.

The coalition even swept traditional bastions of "Chavismo," the movement named after former President Hugo Chavez, including the Caracas slums and Chavez's home state of Barinas.

New legislators plan to launch investigations into corruption and pressure the government into publishing economic data such as inflation, which have not been divulged in a year.

Despite an overwhelming mandate for change, there is little the new opposition-controlled legislature will be able to do about unwieldy currency and price controls, which are a major factor in the economic problems.