"Having said all that, it doesn't matter how much was spilled because the compensation will be based on the financial loss that people have suffered because of the spill in the lagoon," he said. "And that is a matter of dispute between us and the claimant."
Leigh Day said that 15,000 fishermen and 31,000 inhabitants of 35 villages were affected in and around the Bodo lagoon and its associated waterways. The law firm says independent experts estimate between 500,000 and 600,000 barrels were spilled, devastating the environment that sits amid 90 square kilometers (35 square miles) of mangroves, swamps and channels.
"The majority of its inhabitants are subsistence fishermen and farmers. Until the two 2008 spills Bodo was a relatively prosperous town based on fishing," the firm said in a statement. The spills have destroyed the fishing industry and environment there, it said.
"Those communities are still having water shipped into them. But it's patchy, and we fear many of those communities are drinking from poisoned wells," Leader, the Leigh Day lawyer, said.
But Shell says such estimates are high.
Shell spokesman French said the company did not have access to the area to clean it up, and that not all oil spilled was a result of the company's operations. Shell blames most of the spills in the region on militant attacks or thieves tapping into pipelines to steal crude oil, which ends up on the black market.
Nigeria, one of the top crude oil suppliers to the United States, requires companies to promptly clean up oil spills but the policy is not enforced.
Both parties have said they hope to reach an agreement by the end of the week.
Neither side would discuss possible settlement figures. Britain's Guardian newspaper reported that the company is thought to be offering about $20 million in compensation while the villagers seek $200 million.
Local communities remain largely hostile to Shell and other oil firms because of environmental damage. Some environmentalists say as much as 550 million gallons of oil have been poured into the delta during Shell's roughly 50 years of production in Nigeria.
The United Nations has recommended that the oil industry and Nigeria's government set up a fund, with an initial injection of $1 billion, to begin what could be a 30-year cleanup and restoration project in the oil-stained region.