LONDON, April 26 (Reuters) - Trafigura said on Monday that it had sold the first cargo of naphtha, a refined oil product used in plastics, for which the carbon emissions -- from production to delivery -- were offset. The move reflects a growing trend among oil and gas firms to market their products as cleaner and to secure a future for the fossil fuel industry amid an accelerating energy transition. Trafigura said in a statement it had sold the cargo, which was shipped last week from Corpus Christi, Texas and is due to arrive in the Brazilian Port of Aratuo, to Brazil’s Braskem. The global commodities trader said that it had used the most energy efficient vessel available at the time and the speed of the voyage was adjusted to reduce emissions further. The Geneva-based company added that the cargo was offset with nature-based projects in Indonesia known as REDD+, which are independently verified by the Verified Carbon Standard. REDD projects emerged from the UN climate negotiations and aim to reduce emissions from deforestation and forest degradation. REDD+ goes beyond this to include sustainable forest management, conservation and increasing forest carbon stocks. Rival trading firm Vitol began offering green liquefied natural gas (LNG) cargoes last month, whereby the offsets would mitigate emissions from wellhead to delivery. In January, Occidental Petroleum said it had sold the first ever 100% carbon-neutral shipment of crude to India. Some companies have begun seeking a premium price for what they call cleaner petroleum products. Trafigura did not detail the costs of the cargo versus a regular naphtha shipment but said it was a service provided to Braskem. Although carbon credits do not reduce the pollution from a barrel of oil, their proponents say they help finance clean-energy efforts that otherwise would not be profitable. (Reporting by Julia Payne; Editing by Alexander Smith)