President Nicolas Maduro of Venezuela has announced a mandatory fingerprinting system in supermarkets to combat food shortages and smuggling.
He said the system would stop people from buying too much of a single item.
But the opposition in Venezuela rejected the plan, saying the policy treated all Venezuelans as thieves.
Critics said fingerprinting consumers of staple products was tantamount to rationing and constituted a breach of privacy.
Up to 40% of the goods which Venezuela subsidises for its domestic market are smuggled to Colombia, where they are sold at much higher prices, the authorities say.
“The amount of staples smuggled to Colombia would be enough to load the shelves of our supermarkets,” Gen Efrain Velasco Lugo, a military spokesman, told El Universal newspaper earlier this week.
The opposition blames what it says are the failed left-wing policies of the past 15 years – initiated by late President Hugo Chavez – for the country’s economic crisis.
Dissatisfaction with the shortage of many staples, as well as rampant crime and high inflation, led thousands of people in the western Venezuelan states of Tachira and Merida to take to the streets in January.
The protests quickly spread to the rest of Venezuela, which faces similar problems.
Earlier this month Venezuela launched an anti-smuggling operation on its border with Colombia.
It deployed 17,000 troops along the border and began closing all the crossings at night.
The one-month ban will be lifted in mid-September.
The decision to close the border was agreed with Colombia, where the smuggling of cheap goods from Venezuela is also seen as a major problem.
The Colombian government says it leads to a big loss in t