Nigeria, June 15 -- Nigeria's foreign reserves plunged to its lowest level in four years last week, hardly reflecting the marginal gains in rising oil prices in recent months, central bank figures show.

The reserves fell by $222.3 million between May 31 and June 10 to $34.0 billion, according to figures published by the Central Bank of Nigeria.

The last time it fell below that mark was between June and July of 2017.

Before recording a gradual slump, the reserves had reached $36.5 billion at the start of the new year. The rise, which began mid-December 2020, was buoyed by a steady rise in oil prices in the international market.

It was unclear why the reserves fell at a time of rising crude oil prices, although similar declines in the p...