Nigeria's foreign exchange reserves fell to $30.49 billion as of May 25, the lowest level since April 18 and down 0.87% from a month ago, Central Bank data showed on Wednesday.

The forex reserves were up 15.27% year-on-year, the data showed.

Nigeria’s economy shrank by 1.5% in 2016 in its first annual recession in 25 years, hit by acute shortage of hard currency and lower revenue from oil sector as world crude prices remained under pressure.

To manage the crisis in the foreign exchange market, the Central Bank has been intervening on the official market to try to narrow the spread between the official interbank and black markets.

It has sold over $4 billion since February, but analysts doubt that this pace can be sustained. It now appears the intervention scheme is beginning to have negative impact on the foreign exchange reserve.

The reserves have grown by $4.4 billion year to date due to recovery in global oil prices and increased production. The reserves stood at $26.09 billion at the beginning of the year and $26.45 billion a year ago.