Venezuelan President Nicolas Maduro is vowing to expand price controls in a bid to battle rampant inflation.

Maduro said on Tuesday that he will increase enforcement of rules that limit the profit retailers can make. He also said he would expand price controls to all goods and services, and said no profit margin should exceed 30 per cent.

He did not provide details about how the new system would be put in place.

Critics blame existing price controls for increasing shortages in the country, partly because many businesses say they cannot cover costs without getting a government-subsidised exchange rate, and that can be hard to obtain at a time when falling oil prices have squeezed government revenues.

The plummeting free-market value of Venezuela's currency, the bolivar, makes it hard to import goods independently.

Prices are currently regulated on products ranging from pantry staples to Barbie dolls.

Meanwhile, Venezuela's socialist party-controlled Congress made a formal request on Wednesday for an investigation into the head of the country's largest private company, the food supplier Empresas Polar.

Congress President Diosdado Cabello released a recording last week of billionaire Polar CEO Lorenzo Mendoza speaking with an economist on the phone about the possibility of an international bailout of Venezuela's sinking economy.

Mendoza, who has often come in for attack from leading government officials, suggested in the call that the International Monetary Fund could create an adjustment plan for the country.

Mendoza has confirmed that the telephone conversation was real, but denounced its secret recording and later distribution. He denied charges that he is conspiring against the government.

Maduro, on Sunday, joined in calls for his prosecution.