ABUJA, April 25 (Reuters) - Nigeria's oil regulator on Thursday clarified that recent changes to fuel sulphur content standards for diesel are part of a regional harmonisation effort, not a relaxation of regulations for local refineries.

Last week, an S&P Global report noted a significant shift in the West African fuel market after Nigeria altered its maximum diesel sulphur content from 200 parts per million (ppm) to around 650 ppm, sparking concerns it might be lowering its standards to accommodate domestically produced diesel which exceeds the 200 ppm cap.

But the Nigerian Midstream and Downstream Petroleum Regulatory Authority (NMDPRA) said it was only adhering to a 2020 decision by the Economic Community of West African States (ECOWAS) which mandated a gradual shift to cleaner fuels across the region.

High sulphur content in fuels can damage engines and contribute to air pollution.

Currently, the ECOWAS rule allows locally produced fuel to have a higher sulphur content until January 2025. At that point, a uniform standard of below 5 ppm will apply to both domestic refining and imports from outside West Africa.

NMDPRA chief Farouk Ahmed told Reuters the new limits comply with the decision by ECOWAS that mandated stricter fuel specifications, with enforcement starting in January 2021 for non-ECOWAS imports and January 2025 for ECOWAS refineries.

"We are merely implementing the ECOWAS decision adopted in 2020," Ahmed said.

"So a local refinery with a 650 ppm sulphur in its product is permissible and safe under the ECOWAS rule until January next year where a uniform standard would apply to both the locally refined and imported products outside West Africa", Ahmed said.

Ahmed said importers were notified of the progressive reduction in allowable sulphur content, reaching 200 ppm this month from 300 ppm in February, well before the giant Dangote refinery began supplying diesel.

Importers were previously permitted to bring in diesel with a sulphur content between 1,500 ppm and 3,000 ppm.

The shift to cleaner fuels aligns with global environmental efforts and ensures a level playing field for regional refiners. (Editing by Elisha Bala-Gbogbo; editing by David Evans)