MOSCOW (Reuters) - Gazprombank, Russia’s third biggest lender by assets, has sold its indirect stake in the Petrozamora joint venture in Venezuela, a source at the bank said on Thursday.

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Gazprombank, in a written reply to Reuters questions, confirmed it had quit the Petrozamora joint venture, but gave no further details. The venture’s majority owner, Venezuelan state oil firm PDVSA, is under U.S. sanctions.

Gazprombank has a minority stake in a firm called GPB Global Resources which in turn owns 40 percent of Petrozamora, according to the GPB Global Resources website.

PDVSA owns the remaining 60 percent in Petrozamora, which was set up in 2012 initially to develop two Venezuelan oil fields, the website said. The number of fields has since increased.

“An indirect minority stake in Petrozamora JV was sold to a group of investors which have no connection to the Gazprombank group,” the source in the bank said. “As a result, Gazprombank now has no investment projects in Venezuela.”

The identity of the buyer was unknown. The source said that Gazprombank has sold its stake in GPB GR as well. GBP GR did not immediately reply to a Reuters request for a comment.

In November 2013, Gazprombank, GPB GR, Petrozamora and PDVSA signed an oil prepayment facility of up to $1 billion to finance the investment program and operational activity of Petrozamora JV.

Russia is a major investor in Venezuela but this poses risks to Russian companies now that the United States has imposed sanctions on PDVSA and other entities linked to it. Some Russian firms are trying to reduce their exposure.

Gazprombank decided to freeze the accounts of PDVSA and halted transactions with the firm, a Gazprombank source told Reuters last month.

Russia’s second biggest bank, VTB, has begun procedures to hand over its stake in a Russian-Venezuelan bank, Evrofinance Mosnarbank, to the Russian state property agency, sources familiar with the deal told Reuters this week.

The United States imposed tough, new financial sanctions on Jan. 28 aimed at blocking Venezuela’s President Nicolas Maduro’s access to the country’s oil revenue as its aimed to support Venezuelan opposition leader and self-proclaimed interim president Juan Guaido.

Russia’s Rosneft, the world’s top listed oil company by output which has lent billions of U.S. dollars to Venezuela in the past and has a number of upstream projects in the country, continues its operations and to receive oil from PDVSA.

According to lawyers and traders, the terms of the sanctions mean that Rosneft can continue its oil and oil product operations with PDVSA at least until April 28.

However, U.S. Secretary of State Mike Pompeo this week accused Rosneft of providing a financial lifeline to the administration of Venezuelan President Nicolas Maduro, who Washington says is no longer the legitimate head of state.