Anglian Water bosses should face jail if they fail to clean up their act and curb pollution of the region's rivers, the Environment Agency has said.

The watchdog has called for the extreme measures as a way to force water companies to do more to prevent harmful 'spills', which in the most extreme cases can involve sewage pouring into waterways.

The agency's chairwoman Emma Howard Boyd urged the action following the publication of a report which identified Anglian Water as the water company responsible for the highest number of the most serious category of pollution incidents last year.

In total, there were 14 such cases in the Anglian Water area.

The company has vowed to improve its performance and said the figures were due to a period of extremely high rainfall and severe flooding.

The company was one of four - alongside Thames, Wessex and Yorkshire Water - rated only two stars in the Environment Agency's annual environmental performance report, which means they require significant improvement.

Two others - Southern and South West Water - fell to one star, the bottom rating, with performances described as "terrible across the board" by Ms Howard Boyd.

She called for prison sentences for chief executives and board members whose companies are responsible for the worst spills and wants company directors to be struck off, so they cannot move on in their careers, after illegal environmental damage.

Anglian Water has already been convicted for river pollution incidents three times so far in 2022.

Speaking in general terms, rather than specifically about Anglian Water, Ms Howard Boyd said: "Company directors let this happen. We plan to make it too painful for them to continue like this.

"The amount a company can be fined for environmental crimes is unlimited but fines currently handed down by the courts often amount to less than a chief executive's salary."

Anglian’s latest annual report shows it is paying £92 million in dividends to its private shareholders this year.

Owners of the privatised company include the Abu Dhabi Investment Authority and Canada Pension Plan Investment.

Earlier this year, the firm raised bills for its seven million customers.

The agency’s report shows the firm was responsible for 258 pollution incidents in total last year.

The 14 worst involved sewage pollution but others involved incidents from pumping stations, treatment works and pipes.

Environmentalists have warned pollution was putting rivers, coasts and the wildlife that depends on them at ever greater risk.

Ali Morse, water policy manager at the Wildlife Trusts, which includes Norfolk Wildlife Trust, said: "The damage caused to nature is shocking and customers will want to see these figures coming down rapidly."

A spokesperson for the Department for Environment, Food and Rural Affairs said: “This report shows that water companies are ignoring their legal responsibilities.

“We will not tolerate this behaviour and we will take robust action if we don’t see urgent improvements.”

Mike Keil, senior director at the Consumer Council for Water, said the findings cast “serious doubt over whether some water and sewerage companies can be trusted to look after the water environment”.

"It's also an insult to customers who have told us they want to see companies do more to improve rivers and the habitats that wildlife depend on,” he added.

Earlier this year Robin Price, director of quality and environment at Anglian Water, admitted that dumping sewage into Norfolk’s rivers and beaches was “completely unacceptable”.

The company announced a major initiative to clean up and revitalise rivers and said that it will eliminate all serious pollution from its waterways by 2025 and reduce milder pollution by at least 45pc.

It has also announced plans to launch a fund to help monitor the region's rivers, as well as work towards reintroducing species such as salmon, burbot and beavers.

Responding to the latest performance report, a company spokesman said: "Protecting, restoring and improving our region’s environment is at the heart of our business, and we take this responsibility incredibly seriously.

"While we’ve performed well in some areas, we are not where we need to be in others. We’re extremely disappointed to have dropped to a two-star rating last year.

"This rating reflects a challenging year, especially given the extreme rainfall and widespread flooding we saw at the start of 2021."

Untreated sewage leaks lead to fines

Serious pollution incidents have seen Anglian Water fined three times already this year.

Raw sewage flooding into a river at Yaxley in Cambridgeshire for hours was blamed on the company’s slow response. It was fined £18,000 for failures at a pumping station in 2019.

The water company and a contractor were also fined a total of £60,000 after raw sewage leaked into a river in Peterborough killing more than 2,400 fish.

It’s believed that untreated sewage could have been discharging for up to 10 hours.

Levels of ammonia monitored downstream from the discharge were found to be 200 times higher than average water quality standards.

Anglian was also fined £300,000 after pollution from a water pumping station caused the death of over 5,000 fish in an Essex river.