Central bank of Nigeria said on Wednesday it offered $250 million in currency forwards, to be settled within 30 days, to airlines, fuel importers and agriculture businesses. It also offered $100 million on the spot market for foreign travel, school and medical fees as part of efforts to boost dollar liquidity and prop up the ailing naira currency. The central bank said forex purchase will be paid for immediately in naira after the release of bid rates. The naira closed on Wednesday at 306.10 per dollar on the official market and 410 on the black market. The bank has intervened on the forward market in the last few weeks in an attempt to meet demand but customers with an immediate need for dollars have piled back into the black market, causing the naira to begin to weaken in that segment.