ABUJA - The Central Bank of Nigeria raised its benchmark interest rate to 13% from 11.5%, Governor Godwin Emefiele said on Tuesday, surprising analysts who had been expecting the Monetary Policy Committee (MPC) to keep the rate unchanged.

Emefiele told a news briefing the rate hike was necessary to tame inflation, which quickened to 16.82% in April, its highest in eight months amid a fragile economic recovery.

Food and energy prices are rising in Africa's most populous country after Russia's invasion of Ukraine pushed up oil prices and disrupted supplies of commodities like corn and wheat.

Emefiele said six members of the MPC voted to increase the main lending rate by 150 basis points, four of them by 100 basis points and one by 50 basis points.

It was the biggest rate hike since 2016 when the central bank increased rates by 200 basis points.

"(MPC members) felt that tightening will help rein in inflation before it assumes a galloping trend," Emefiele said.

"The committee decided to raise monetary policy rate for the first time in two and a half years to rein in the current rise in inflation as members were of the view that the continued uptrend may adversely impact growth."

The rate hike sent the yield on Nigeria's longest 30-year bond soaring 75 basis points to 13.8%, traders said.

Razia Khan, chief economist for Africa and the Middle East at Standard Chartered, said the rate increase raised questions about whether this could be a precursor to a change in the central bank's policy on foreign exchange.

"This could be the most important signal yet of eventual FX policy intentions ... but we will not really know until we see whether and how much market rates reprice," she said.

Tightening policy could help moderate domestic borrowing by the government, which has seen the amount it spends on servicing its debt increase significantly in recent times, said Emefiele.

The central bank governor, who ended his presidential ambition on Monday, said the economy was expected to expand 3.25% this year, lower than the federal government's projection of 4.2% growth.

(Writing and additional reporting by MacDonald Dzirutwe and Estelle Shirbon, Editing by Catherine Evans and Mark Potter)