Venezuela will begin installing some 20,000 fingerprint scanners at supermarkets nationwide in a bid to stamp out hoarding and panic buying, which the government blames for long lines and widespread shortages of basic goods.

The oil-rich nation has been selectively rolling out the rationing system for months at state-run supermarkets along the western border with Colombia, where smuggling of price-controlled goods is a major problem.

On Saturday, President Nicolas Maduro said that seven large private retail chains had voluntarily agreed to install the scanners.

"I ask for the the comprehension of all of Venezuela, to understand this problem, because there is a lot of manipulation taking place," Maduro said at the inauguration of a state-run supermarket.

Economists say the effort is bound to fail. They blame decade-old price controls for destroying local manufacturing and attracting smugglers who can resell the goods on the black market and in Colombia for huge gains.

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In recent days, those profits have become juicier as a result of Venezuela's tanking currency. The bolivar has slid 35 percent in the past two weeks on the black market and now trades at nearly one-fortieth the official rate used to import food, according to DolarToday, a website that tracks the illegal rate based on currency trades along the border.

The fall of world oil prices by nearly half since November is also diminishing the supply of dollars available to import everything from milk to cars. Crude oil accounts for 95 percent of Venezuela's exports.

As Venezuela's economic crisis deepens the government is increasingly lashing out at its opponents and the United States, which it says is trying to sow instability and set the stage for a coup.

But many Venezuelans point to Maduro. Recent polls say the embattled president has a 22 percent approval rating, the lowest since the start of the socialist revolution 16 years ago by the late President Hugo Chavez

On Friday, a delegation of visiting South American foreign ministers announced that the region would help Venezuela address the shortages.

But many in the opposition expressed dismay that the 12-nation Unasur bloc did not take a tougher stance against the government amid what they say is an impending humanitarian crisis.