SINGAPORE, Dec 26 (Reuters) - BP Plc's joint venturein Russia, TNK-BP, has sold a February ESPO crudecargo at a lower premium than previous deals for cargoes loadingin the same month, traders said on Wednesday. ESPO premiums have slipped from their highest in a yearfollowing weaker sentiment for rival Middle Eastern grades asmost refiners have completed their purchases for February. The cargo for Feb. 22-25 loading was sold likely to aChinese end user at a premium between $4.70 and $4.75 a barrelto Dubai quotes, traders said.