Underestimated: Oil gushed unabated for for three months during the 2010 disaster. New evidence suggests that that BP vastly understated the scale of the leak for weeks

Kurt Mix, the former BP employee, has been charged with two felony counts of obstruction of justice for allegedly destroying hundreds of text messages during the incident.

It is alleged that Mix deleted the messages he sent to a supervisor, including reports that the amount of oil leaking into the Gulf of Mexico was bigger than BP were publicly stating at the time.

As reported in the Huffington Post, on Friday Mix's lawyers asked a federal judge in New Orleans for permission to present thousands of emails at the trial in February 2013.

His attorneys argue that as Mix did co-operate with federal officials about the size of the leak, he was not part of a cover-up. But the emails do suggest a large internal effort at BP to hide the true size of the leak.

BP pleaded guilty to 14 felony counts relating to the disaster in November. The initial explosion killed 11 men working on the Deepwater Horizon and injured 17 others.

Last month's plea agreement included 11 manslaughter charges and one felony count for obstruction of justice. This related to BP's false statements made to Congress about the amount of oil leaking from the well.

BP will pay $4.5 billion in fines and other fees to settle the charges, the largest payment of its kind in U.S. history.

According to the Huffington Post, just two days after the explosion, Mix emailed a supervisor estimating that the out-of-control well could be leaking between 62,000 and 146,000 barrels of oil per day.

Only two days later, BP told the U.S Coast Guard that their best estimate for the leak was 1,000 barrels per day.

Since the disaster a scientific group concluded that the well was leaking 62,000 barrels per day at the beginning of the disaster.

Huffington Post also reports on another email, in which a Norwegian oil consultant analyzed video leak sent to him by Mix.

'I do not think it can be ruled out that the flow at seabed is in the order of 40,000,' said the consultant.

Only four days later, BPs' current chief executive, Bob Dudley, publicly defended the company's leak estimate (sent to Congress and federal officials) of 5,000 barrels per day.

Dudley claimed that estimates that the oil flow was much higher were just 'scaremongering. 'Five thousand barrels a day, while inexact, is the best estimate of the industry experts,' Dudley said.