The Nigerian naira strengthened against the U.S dollar on Friday on the interbank market following sales of around $72 million by two local units of oil companies, traders said. The naira closed at 157.30 to the dollar on the interbank, compared to 157.50 close on Thursday. Dealers said units of Chevron sold $53 million, while Addax Petroleum, which is owned by China's Sinopec Group sold $19 million to banks, boosting dollar liquidity in the market and provided support for the local currency. An increase in dollar inflows from oil multinational companies and offshore investors into local debt instruments has supported the naira since the start of the year. "The outlook favours a slight depreciation of the naira because we are not expecting much dollar inflow next week," one dealer said.