Royal Dutch Shell's Bonga oilfield in Nigeria will undergo maintenance in March and April, though the impact on production and exact dates are still being finalized, a spokesman said.

Shell operates the offshore field via its Nigerian subsidiary SNEPCo. In March, around 153,000 barrels per day (bpd) of crude were due for export, according to a loading program.

"The Bonga FPSO will be undergoing scheduled maintenance and project activities in addition to regulatory inspections during March and April. Exact dates and production impacts are currently under review,” the spokesman said.

So far, no April loading program has emerged. Traders said just two cargo loading dates came out for April 1-2 and 11-12, the first of which is likely a deferral from March.

Bonga, known as Bonga North West, is located in the OML 118 block. Shell announced plans to develop another field called Bonga South West inside the same area. The $10 billion development is expected to add 200,000 bpd, roughly 10% of Nigeria’s current oil production.

However, uncertainty over future fiscal terms has delayed a final investment decision.

(Reporting by Julia Payne and Noah Browning; Editing by Mark Potter and Susan Fenton)