A cooperative organisation has been launched to advocate for and raise money for independent media free from state or corporate control.

The Media Fund has launched days after the BBC’s Today programme presenter Nick Robinson said alternative news sites were part of a “guerrilla war” against the BBC and other mainstream media outlets. It aims to give way to digital platforms to counteract an “old media system” dominated by broadcasters and newspapers, which it says displays a rightwing bias. It has so far partnered with 21 outlets, including Novara Media, the New Internationalist, Open Democracy and the Bureau of Investigative Journalism.

To partner with the fund, these outlets have to sign up to the National Union of Journalists’ code of conduct, demonstrate a commitment to factual and accurate reporting, and within a year of joining become fully unionised workplaces. New partners must be approved by existing partners, suggesting that rightwing outlets are unlikely to be selected.

“The idea is that any media organisation that’s a partner with us is one you can trust in an age of understandable caution about your sources,” said Thomas Barlow, the fund’s strategic director. “We’re going to try and be that stamp of respectability for independent media.”

Last week, leading alternative news site the Canary was accused of peddling fake news after it published an article about Laura Kuenssberg, Robinson’s successor as BBC political editor, that was swiftly debunked.

The press regulator, Impress, had received 48 complaints about the article by Thursday. The left-of-centre website was criticised on social media because Kuenssberg has faced hostility on and offline in her role and was reportedly accompanied by a security guard at the Labour conference after receiving threats.

The Canary is not currently partnered with the Media Fund, but “discussions will be had” at a future stage, Barlow said, adding that the tabloid press, including the Mail, the Sun, and the Express, “openly disrespect and attack the BBC on a regular basis”.

Barlow said: “It’s funny that someone like Nick Robinson won’t openly discuss their factual inaccuracies. We know why: Robinson’s not as afraid of the independent media as he is of the Murdoch press, and he shares more political and personal affinity with the tabloid press. It’s not just that he’s a Conservative, it’s that the BBC’s news agenda is largely set by the tabloid press.”

There has been a growing trend in Britain of leftwing activists setting up their own news and media sites to take on the established press, after what they saw as unfair coverage of Jeremy Corbyn and his Labour party. While their subject matter and approach varies, most if not all of the outlets distrust the “MSM” and use social media to deploy their message. Barlow, who was the business and social media manager at Real Media, said their reach of about 50,000 went up to 1.5 million during the general election.

Similarly, Novara, once labelled Momentum’s “armed police”, has 200 contributing writers, 700 supporters and 10,000 committed viewers and listeners. Its creator, Aaron Bastani, has said Novara’s Facebook content reached 3 million people during the general election.

Momentum itself had massive networks to distribute its content and used new technologies to help mobilise Labour members, which was fundamental in winning many marginal constituencies.

“People were being dragged into cultural wars around race and immigration, but only so many people are motivated by that,” Barlow said. “After a while you’re really going to have to address some underlying problems and issues. The media and politicians aren’t doing that. And the ones who are aren’t given a fair shake at all.”

The established press, he added, not so much censors but curtails certain types of discussion. “Certain ideas are new in public discourse and need time to be discussed. For instance, Labour’s economic programme. It’s relatively middle of the road for a European democracy and a developed democracy, but in Britain, where we’ve had liberal discourse for 35, 40 years, and it’s become the established norm, talking about something like nationalising railways requires a bit of time.”

Ash Sarkar, a senior editor at Novara Media, said the traditional media had failed to recognise a change in politics. “Establishment media don’t understand it because fundamentally, their idea was that the centre of power and the centre of parliamentary politics was the same thing.”

The Media Fund, made up of nine people, began accepting donations on Sunday when its website launched, before a hard launch in November – one year after it crowdfunded £10,000 to get off the ground.

Barlow argued that the media, including the BBC, needed to “get with the times” and recognise that huge changes are happening. “If we don’t get a Corbyn, we could get a Trump,” he said. “At the moment they seem to be egging on a Trump.”

• This article was amended on 6 October 2017 to remove a quotation that contained incorrect information about complaints data.