Nigeria's crude oil production fell below 1 million barrels per day in August, figures from its regulator showed, as the nation grappled with rampant theft from its pipelines and years of underinvestment.

The head of Nigerian Upstream Petroleum Regulatory Commission Gbenga Komolafe said in a statement on Tuesday that there could be more fundamental issues hobbling output "beyond the much touted issue of crude theft."

He did not give details but added that oil companies would be expected to "present their work programme performance, acreage status, divestment plans (if any), field development plan implementation status, upstream investment in the last five years" among other things.

"The Commission would also insist on knowing their gas development strategy, gas reserves commitment status and domestic gas delivery obligation performance," said Komolafe.

He said the latest action was meant to ensure transparency and accountability in the oil industry.

(Reporting by Camillus Eboh, writing by MacDonald Dzirutwe, editing by Sandra Maler)