Jeremy Corbyn will use an appearance at Edinburgh television festival to criticise the role of billionaire owners, and large internet companies such as Facebook, in the British media.

“A strong, diverse and independent media is a cornerstone of a healthy democracy and society,” Corbyn said on Friday in a preview of the speech next week.

“I hope to offer some perspectives on the UK media and its role today, discuss how good journalism challenges the powerful and what is holding it back in the digital age of tech giants and unaccountable billionaires.”

The Labour leader has agreed to give the Alternative MacTaggart lecture, one of the major events at the British television industry’s annual get-together in the Scottish capital.

His speech will be followed by a Q&A session with the actor Maxine Peake, a longtime supporter of Corbyn who has promised to ask him about “life, policy, culture and which soap character he most identifies with”.

Corbyn has been increasingly willing to directly criticise the media. This week, he decided to confront most of the British newspaper industry head on, formally complaining to the press regulator Ipso about how six national outlets had covered his decision to take part in a wreath-laying ceremony at a Tunisian cemetery where Palestinian activists are buried.

He has generally had a better relationship with broadcasters than newspapers. During the 2017 general election campaign, Corbyn’s team focused on using TV news channels to get their message across to the public, in the belief that the heavily regulated world of broadcasting meant he would be guaranteed to receive more coverage.

Despite Corbyn’s frequent battles with the media, the Labour party remains vague on what it would do to reform the industry. Its 2017 election manifesto pledged to hold a national review of the decline of local news outlets and the ownership of national media businesses. It also pledged to secure funding for the BBC and put in place clearer rules on who is fit and proper to own or run TV and radio stations.

Media policy is still within the purview of the party’s deputy leader, Tom Watson, who is also the shadow culture secretary. This year, he came close to forcing the government to hold a new public inquiry into the activities of the media industry and social media companies.