FILE PHOTO: A logo of Russian state oil firm Rosneft is seen at its office in Moscow, October 18, 2012. REUTERS/Maxim Shemetov/File Photo

HOUSTON (Reuters) - Russian oil firm Rosneft has struck deals with several buyers for almost its entire quota of Venezuelan crude for the remainder of the year, traders told Reuters on Wednesday, the first time it has conducted such a large sale of the OPEC member’s oil.

Rosneft, which is taking a growing volume of Venezuelan crude and products while extending credits to President Nicolas Maduro’s government, previously had resold the barrels in the United States and Asia through trading firms, according to PDVSA’s [PDVSA.UL] internal documents.

The new sales mechanism is similar to the one used by Andes Petroleum, a China National Petroleum Corporation (CNPC) and Sinopec joint venture, to sell its quota of Ecuadorian crude by awarding the barrels through annual or biannual tenders, one of the traders said.

It was not immediately clear which refiners agreed to buy the oil or the volume of the tender, but traders said the buyers included U.S. firms. Among the largest buyers of Venezuelan heavy crude in North America are Valero Energy Corp, Citgo Petroleum [PDVSAC.UL], Phillips 66, Chevron Corp and PBF Energy Inc, according to Thomson Reuters data.

Rosneft, Chevron and Valero did not immediately respond to requests for comment. U.S. refiners Phillips 66 and PBF Energy declined to comment on commercial arrangements.

Some of these refiners recently have struggled to purchase Venezuelan oil directly from PDVSA as banks based in the United States have refused to extend the letters of credit the buyers need to complete imports from Venezuela.

Rosneft’s deliveries of Venezuelan oil will occur during September through December. The crude grades offered include diluted crude oil (DCO), a blend of extra heavy oil and heavy naphtha, according to the sources.

Russian oil firms Rosneft and Lukoil since May have received some 250,000 barrels per day (bpd) of crude and refined products from Venezuela, according to the PDVSA’s internal documents.

Venezuela’s oil deliveries to the United States have declined in recent years amid falling production, commercial issues, and sanctions on Venezuelan officials. It has relied on deliveries to Russian oil firms to repay loans and swaps.