Steve Coogan has accused United Utilities of “greenwashing” and “PR spin” as he criticised the company for putting sewage into Lake Windermere.

The I’m Alan Partridge star joined a protest outside the North West water company’s offices near the lake as he called on the Government to compel them to clean up England’s largest lake rather than pay huge dividends to shareholders.

He told ITV’s Good Morning Britain: “United Utilities have a big PR machine and they put nice fancy offices up like this and say we’re working together with the people of Windermere but it’s all a smokescreen to distract attention from what they’ve been doing over the last 30 years, which is putting treated and untreated sewage into Lake Windermere.

“It’s to such an extent that there are toxic levels of algae, there are algae blooms that show the nitrate levels are like through the roof. And they’ve been doing this year on year.”

He added: “They have been paying out record dividends to shareholders, there’s no excuse for this. We’re telling them to stop putting sewage in the lake and take out what they put in.”

Coogan said the company should not be allowed to pass on the cost of cleaning up to the lake to bill payers but rather should deny their shareholders a dividend for a few years.

He said: “Either they need to do it themselves, which I doubt they will because they are powerless to their shareholders, or the Government needs to act.”

Addressing why is it legal for the company to put sewage in the lake, Coogan said: “What makes it more obscene is it’s almost like the business model is predicated on the ability to put sewage in a lake and not do anything about it, because to sort that problem would require a huge investment that they are not prepared to put into it.”

The actor said the money the company is investing in addressing the issue is “chicken feed” in comparison to the profits and the grants are “PR spin and greenwashing”.

He added: “It is all to stop people looking at the fundamental problem, which is they are the biggest polluters in this country, the biggest water utility company pollutes British waterways.

“The lakes are there for everyone, people who can’t afford holidays abroad to be able to use the lake for recreation and it’s threatening that.”

Asked how he could defend dumping untreated sewage into the lake, Chris Matthews, of United Utilities, told the programme: “We share the concerns that Steve has expressed there, and many other people, about the overflow operations and the impact on local water courses and are investing to tackle this problem.

“We are investing to tackle this problem here at Windermere, we’ve spent £75 million on our wastewater treatment to halve the amount of phosphorus that goes into the lake.”

He added: “We are taking this problem extremely seriously as part of a huge investment programme.”

He told the show that customer bills will be increasing to help fund the programme. saying: “It’s going to be about £25 a year that bills will go up, about £2 a month, to help fund what is a  £14 billion plan.”