During the long-delayed and high-profile trial, which is due to start in New Orleans on February 25, US government prosecutors will try to pin the blame for the 2010 spill on BP and secure a fine that could reach $20bn (£13bn).

Despite the unwelcome publicity the trial is expected to generate in the states that line the Gulf, City investors say that the region must remain central to BP’s future.

“The Gulf of Mexico is a key area,” said one top-five shareholder who asked to remain anonymous. “It is part of the investment case in BP.”

In late 2011, BP was awarded its first permit to drill in the Gulf since the spill and has since secured more licences. However, Bob Dudley, chief executive of BP, said this month that given the scale of its existing operations in the Gulf “it is questionable how much we want to add to that”.

While there is appetite in the City of London for BP to expand in the Gulf, there is also a strong desire for the company to avoid a trial that legal experts warn could stretch into 2014.

“The market wants a resolution,” said Richard

Marwood, a fund manager at Axa Investments, which is also a BP shareholder. “Many are half expecting that something will be sorted out at two minutes to midnight.”

The trial was scheduled for early last year, but was delayed hours before it was due to start after BP struck a deal with thousands of businesses on the Gulf coast that were hit by the spill.

Last November, it reached a $4.5bn criminal settlement with the US Department of Justice, but that still leaves next week’s civil trial to determine who was to blame for the spill and how much oil was spilt, as well as assess the UK company’s efforts to stop the spill and then contain the oil.

Efforts to strike a last-ditch settlement may be complicated after BP disclosed that the Gulf states are seeking $34bn in damages under the Oil Pollution Act. BP said the figure was based on a “seriously flawed methodology”.

A spokesman for Louisiana’s attorney general told The Sunday Telegraph: “We contend it [the sum] is reasonable considering the damages caused to Louisiana.”