The invention concerns a method for refrigerating liquefied natural gas under pressure ( 1 ), comprising a first step wherein the LNG ( 1 ) is cooled, expanded and separated (a) in a first base fraction ( 4 ) which is collected, and (b) a first top fraction ( 3 ) which is heated, compressed in a compressor (K 1 ) and cooled into a first compressed fraction ( 5 ) which is collected; a second compressed fraction ( 6 ) is drawn from the fuel gas ( 5 ), cooled then mixed with the cooled and expanded LNG ( 1 ). The invention is characterised in that it comprises a second step wherein the second compressed fraction ( 6 ) is compressed and cooled, and a flux is ( 8 ) drawn and cooled, expanded and introduced in the compressor (K 1 ). The invention also describes other embodiments.