Agence France-Presse/Getty Images Ecuador's president, Rafael Correa, left, with Venezuela's then-president, Hugo Chávez, in June 2011.
The sucre was introduced at Mr. Chávez's urging in 2010, taking its name from the Spanish acronym for the Unified System of Regional Compensation. Sucre is also the last name of 19th-century Venezuelan independence leader Antonio José de Sucre y Alcalá. In subsequent years, Mr. Chávez frequently promoted its use.
There are differences between the virtual currencies. The sucre is managed by a board of central-bank representatives, which has helped bolster its use. Bitcoin, by contrast, has no government backing.
In addition, bitcoin can be directly used by its holders. The sucre is a trading currency. Importers and exporters make and receive their payments in their local currencies.
Another difference is that Venezuela has promoted the sucre with the idea it may eventually evolve into a hard, regional currency, along the lines of the euro. Until now, almost all the trading using the sucre has been between Venezuela and Ecuador.
Ecuadorean companies exported $737 million worth of goods to Venezuela using the sucre system in the first nine months of 2013, an 80% increase from the same period in 2012, according to Ecuador's central bank.
That growth has drawn attention from the country's regulators, which are cracking down as fraud involving the virtual currency rises.
Ecuadorean prosecutors have filed money-laundering charges against 19 people, nine of whom have been arrested while the others are still on the run from authorities.
"It's a very big operation, and we're working in coordination with the prosecutors' office in Venezuela," said Galo Chiriboga, Ecuador's top prosecutor. "We've detected criminal organizations that operated in Ecuador, sending money not just to Venezuela but also to other countries."
Mr. Chiriboga declined to provide more details because the investigation is continuing.
Officials from the Venezuelan Embassy in Quito declined to comment on the sucre or the money-laundering investigations.
The heightened scrutiny of the sucre comes as law-enforcement officials and policy makers around the world are paying more attention to the risks posed by proliferation of virtual currencies. China, for example, recently moved to restrict its banks from using bitcoin amid concerns about money laundering. European regulators have warned of the risks of using bitcoin.
In the U.S., the Federal Bureau of Investigation in October announced the seizure of 144,336 bitcoins from the computer of the alleged owner and operator of Silk Road, a website the FBI says was set up to trade in illegal goods, including drugs. The website has been shut down and several individuals have been arrested and charged in connection with it, including the alleged owner, Ross William Ulbricht, who has denied the charges.
For companies in Ecuador, the sucre's appeal is its implicit payment guarantee. A combination of falling oil revenue and currency controls have resulted in a dollar shortage in Venezuela that has left many importers of basic goods hamstrung. Ecuador exports to Venezuela everything from carts to tuna to diapers.
In a typical sucre transaction, a company in Ecuador sends the Venezuelan importer an invoice denominated in U.S. dollars, which is Ecuador's national currency. The Venezuelan company then sends that invoice to the Venezuelan central bank, handing over bolívares. The Venezuelan central bank converts the bolívares to sucre and transfers the sucre to Ecuador's central bank. There, it is converted into U.S. dollars, Ecuador's national currency, and the exporting company receives its payments.
NeoHyundai SA, a distributor of Hyundai Motor Co. vehicles based in Ecuador, exports trucks to Venezuela using sucre. The biggest advantage is the ability "to secure payment without relying on the availability of foreign exchange in Venezuela," said Jose Avila, a marketing manager at NeoHyundai.
In Venezuela, the sucre is also a way to expedite deliveries from outside the country.
Emilia Gómez, an employee at Pavco de Venezuela SA, a company that manufactures and sells pipes and fittings, said it can take as few as 15 days to receive approval for payments when using sucre. Without it, approvals take almost a year.
"The advantage is that is makes the process of importing and paying easier," she said.
But prosecutors in Ecuador say they have uncovered instances when "ghost companies," often set up as joint ventures between Ecuadorean and Venezuelan firms, have sent invoices to Venezuela with inflated prices for goods.