The tender closes on Jan. 25 at 2 p.m. Moscow time (1100 GMT), they added.
It was the first ESPO Blend cargo Rosneft had offered on spot since September 2018, Reuters monitoring showed.
Most of Rosneft's seaborne ESPO Blend cargoes are normally allocated to its term buyer, China's CEFC. In the first half of 2018, Rosneft regularly offered cargoes of ESPO Blend on spot.