Finance Minister Rodolfo Marco and Central Bank President Nelson Merentes were to give details at a news conference at 11 a.m. local time (1030 EST/1530 GMT), the government said.

Venezuela's currency controls have been providing dollars at three different rates: 6.3 bolivars for food and medicine, and two complementary rates of around 12 bolivars and 52 bolivars for other goods through systems known as Sicad I and Sicad II.

But access has been restricted and on the black market the U.S. dollar is selling for nearly 190 bolivars, according to widely referenced website dolartoday.com.

President Nicolas Maduro in January said he would keep the preferential rate of 6.3 bolivars, maintain Sicad I at a yet-to-be-announced rate, and replace Sicad II with a new supply-and-demand driven platform.

Brokerage operators, who have been discussing the new system with officials, told Reuters the idea was to allow the bolivar to trade on that platform at a rate nearer the black market, at least double the current weakest level of 52.

A devaluation would leave the government with more hard currency available to service debt, a move which investors generally interpret positively.

Venezuelan bonds, which have been trading at distressed levels on fears of a possible default, were up across the board in trading on Tuesday morning, with yields on several issues dropping to one-month lows.

The Global 2026 bond's was up 3.130 points in price to yield 26.637 percent while the Global 2022 was up 3.000 points to yield 31.832 percent.

IMPACT FOR U.S. CORPORATE

The brokerage operators, speaking anonymously because they were not authorized to give names, said authorities were projecting the black market price could come down to between 120 and 140 bolivars once the new third system opens.

The Central Bank and state oil company PDVSA would be allowed to sell foreign currency via this mechanism, the sources said, with a projected daily offer of between $30 million (20 million pounds) and $45 million. The central bank would retain a power of veto over all operations, they added.

Venezuela had the worst economic performance in Latin America last year with 2.8 percent GDP contraction and officially-estimated 64 percent inflation.

The 12-year-old exchange controls have steadily reduced dollar disbursals amid declining international crude oil prices, spurring shortages of products such as detergent and milk as companies have been unable to import machinery and raw materials.

The new exchange rate is likely to affect U.S. corporate giants with exposure to Venezuela because the government has not allowed them to repatriate revenue from operations.

At least 40 major U.S. companies, including General Motors Co (>> General Motors Company), household goods maker Procter & Gamble Co (>> Procter & Gamble Co) and drugmaker Merck & Co Inc (>> Merck & Co., Inc.), together carry at least $11 billion of bolivar assets on their books.

The Coca-Cola Co (>> The Coca-Cola Co) said during a conference call on Tuesday that it expects Venezuela pricing provisions will continue to negatively impact net revenue.

(Additional reporting by Daniel Burns in New York; Editing by Andrew Cawthorne)

By Corina Pons and Brian Ellsworth