Nigeria’s oil regulator has asked industry giant Shell to pay $5bn (£3.2bn) for a spill off the country’s southern coast last December.
The disclosure was made during a parliamentary hearing on the matter.
A leak at the Bonga field during a transfer of oil to a tanker led to 40,000 barrels spilling into the Atlantic Ocean.
A Shell spokesperson said there was no need for a fine as everything had been done to prevent environmental damage.
The Bonga field, operated by Shell Nigeria Exploration and Production Company (Snepco), is approximately 120km (75 miles) offshore and produces 10% of Nigeria’s oil exports.
The spill was contained before it reached the shore.
The head of Nigeria’s National Oil Spill Detection and Response Agency urged MPs on the House of Representatives’s environment committee to approve his proposal.
“Although adequate containment measures were put in place to combat the Bonga oil spill, it however posed a serious environmental threat to the offshore environments,” Peter Idabor said.
“The people could not fish after a long period after the spill,” he later told the BBC’s Focus on Africa programme.
“So that’s why we are looking at the damages. If the people said they will not pay, so be it. But we want to make it very clear that it’s wrong for them to say they cannot pay. Are they denying that they spilled 40,000 barrels of crude oil into the waters?” he asked.
But Shell said it believed there no “basis in law for such a fine”.
“Snepco responded to this incident with professionalism and acted with the consent of the necessary authorities at all times to prevent environmental impact as a result of the incident,” a spokesperson for the Anglo-Dutch company said in a statement sent to the BBC.
Most previous oil spills in Nigeria – one of the world’s biggest oil producers – have been onshore. Many have been caused by sabotage or militant attacks.
Last year, a UN report into spills in Ogoniland found that the region could take 30 years to recover.
In March, lawyers representing a fishing community in Ogoniland began a case against Shell in a London court over recent oil spills.