Nigeria's central bank sold $15.83 million to exchange bureaus at a more favourable naira rate than the official market, it said on Tuesday, the second such sale in April and the fourth this year as it moves to boost the supply of foreign currency.

The official market quoted the naira currency at 1,315 per dollar at 1326 GMT, LSEG data showed.

The central bank sold $10,000 each at 1,021 naira per dollar to 1,583 currency exchange operators to meet demand for eligible end-user foreign exchange needs, instructing them to resell at a mark-up not more than 1.5% above the purchase price.

This strategy injects liquidity into the market while attempting to control the naira exchange rate which fell to a record low in February, but is starting to strengthen.

The naira has surged sharply against the dollar, both on the official and parallel markets, after the central bank raised interest rates and lifted restrictions on foreign participation at its fixed-income auctions.

The bank has since started a rate tightening cycle and increased yields on short-term treasury bills to attract foreign investors.

Central bank Governor Olayemi Cardoso has said the bank does not intend to prop up the currency, adding that the roughly $2 billion fall in reserves in the last two months had nothing to do with defending the currency.

(Reporting by Elisha Bala-Gbogbo; Editing by Mark Potter)