Water utility company Thames Water has been fined a record £19.75million plus costs for polluting the River Thames with 1.4 billion litres of raw sewage.

It was hit with the penalty after allowing huge amounts of untreated effluent to enter the waterway in Oxfordshire and Buckinghamshire over the course of months in 2013 and 2014.

The discharge left people and farm livestock ill and killed fish and other animals living in the river, putting anglers and fishermen out of business.

Judge Francis Sheridan has already warned that the firm faces paying its largest ever environmental penalty when he hands down his sentence at Aylesbury Crown Court yesterday.

At a hearing last week he was told Thames Water's record fine for pollution was £1 million, paid in January 2016.

The judge replied that "the fine in this case is certainly in excess of that".

He said: "I have to make the fine sufficiently large that they (Thames Water) get the message."

The sentencing followed a ruling in March 2016 that big commercial organisations which cause environmental pollution can be ordered to pay fines running into tens of millions of pounds.

According to the Environment Agency, which brought the prosecution, the largest fine handed down to a water utility for an environmental disaster was given to Southern Water in December over an incident on Margate Beach in Kent in 2012.

Thames Water admitted 13 breaches of environmental laws over discharges from sewage treatment works in Aylesbury, Didcot, Henley and Little Marlow, and a pumping station at Littlemore.

It also pleaded guilty to a further charge on March 17 over a lesser discharge from an unmanned sewage treatment plant at Arborfield in Berkshire in September 2013.

Thames Water chief executive Steve Robertson said: “We deeply regret each of these incidents at six of our sites during the period 2012-14.

"We asked for these incidents to be considered and sentenced together, because it was clear that our performance in this part of our region, at that time, was not up to the very high standards that we and our customers expect.

“Since then we’ve reviewed how we do things at all levels and made a number of key changes.

"These have included increasing the numbers of staff in key operational roles and investing heavily to improve reliability."