CARACAS, Jan 27 (Reuters) - A group of Venezuelan banks have started issuing debit cards to clients who have accounts in hard currency, a move quietly backed by authorities who want to extend the use of dollars in routine transactions, sources familiar with the measure said. Banks have for more than a year stored cash dollars for corporate clients as part of an economic liberalization under socialist President Nicolas Maduro. For 15 years, dollar transactions were under strict government control. State officials privately told banks to begin allowing clients with dollar accounts to use those funds to carry out transactions denominated in the local bolivar currency, said the four sources, who spoke on the condition that neither they nor their institutions would be identified. The move will help improve liquidity and reduce barriers to commerce in an economy hobbled by sanctions, hyperinflation and widespread shortages, but the sources said they were told that Maduro’s government is not preparing a full dollarization. At least four mid-sized private banks have started issuing the cards, the sources said. State-owned Banco del Tesoro is also advertising a dollar-based credit card on its website. “The bolivar little by little will turn into a currency for transactions, while savings will be in dollars,” one finance executive said. When clients make purchases with the cards, the associated dollars will be offered to Venezuela’s central bank, which will in turn auction the greenbacks as part of its foreign exchange platform, which is generally short of dollars, the sources said. Banks do not yet have permission to make transfers in dollars between clients of different financial entities, the sources said. Venezuela’s central bank, information ministry and bank regulator Sudeban did not reply to requests for comment. In a speech to parliament this month, Maduro said Venezuela will move toward a 100% digital economy and that merchants would be able to use debit cards for dollar accounts. He did not provide details. Venezuelan banks still only offer dollar accounts to a select group of clients, in part to ensure they do not accept funds associated with officials or business people who are sanctioned by the United States for ties to Maduro. The U.S. Treasury did not respond to a request for comment as to whether it was concerned about the rising use of dollars in the Venezuelan economy. But the change will certainly be welcomed by Venezuelan shoppers and merchants, who now rely on workarounds such as makeshift vouchers and customer IOUs to complete dollar-based transactions in an economy with scant access to greenbacks. “You will not suffer anymore for lack of change,” said Banco del Tesoro as part of its advertisements for its new dollar-based debit card. (Reporting by Corina Pons and Mayela Armas, Writing by Brian Ellsworth Editing by Paul Simao)