Nigeria's production cost per barrel of crude oil is down to $23, the state oil company said on Aug. 16, after the country last month said the cost was $29 a barrel, one of the highest levels in the world.

The Nigerian National Petroleum Company (NNPC) did not say in its statement how the firm had driven the cost down by $6 in the three weeks since the government's cabinet approved a national petroleum policy that put the price at $29, using data from Rystad Energy.

The state oil firm did not immediately respond to a request for comment.

The NNPC "has driven down the cost of crude oil production from $78 dollars per barrel as at August 2015 to $23 per barrel representing a 70.5% reduction," the company said.

Oil prices began crashing in 2014 and were under $78 for the whole of 2015.

All producers have worked since the crash to cut their exploration and production costs, with most succeeding in driving them down.

The NNPC now aims "to bring the cost of production to between $17 and $19 for onshore and offshore production respectively," it said.