Some viewers are already irritated by the adverts interrupting shows on the ITV catchup service. But they could soon yearn for the halcyon days of shampoo or insurance commercials after being presented with the faces of Rishi Sunak and Keir Starmer.

ITV is considering taking paid ads from political parties for the first time during the upcoming general election thanks to a loophole in broadcasting law.

The broadcaster told the Guardian it was considering whether to allow political parties to buy space on its ITVX streaming platform. This could leave viewers having Love Island or Saturday Night Takeaway broken up by a lecture on the economy.

Ever since commercial television began in 1955, British political parties have been banned by law from buying television adverts. The idea was that this improved the quality of public debate and stopped wealthy political parties buying their way into voters’ homes – ensuring the UK has avoided the political attack ads that are prevalent during American elections.

But the ban – last updated in 2003 – only applies to traditional television channels and not to streaming television delivered over the internet. With audiences increasingly switching off traditional broadcast channels, the UK’s big political parties are preparing to take advantage of the loophole and pay millions of pounds to insert themselves into living rooms.

Tom Edmonds, who ran digital advertising campaigns for the Conservatives in the 2010s, said politicians were desperate to pay to access screens. He said if British broadcasters did not run such ads, US tech companies would happily take the money. “You are going to see political ads on your TV. A lot of it will go on YouTube because you can get it in HD on your TV,” he added.

In the past, British political parties did not have enough money to buy campaign adverts. But Labour and the Conservatives are set to take advantage of a little-noticed rule change announced last year by Michael Gove, which will increase the amount national political parties can spend on a general election campaign from £19.5m in 2019 to £35m for the next general election.

Edmonds, who now runs the digital consultancy Edmonds Elder, predicted the vast amount of this additional money would go on adverts directly targeting voters. “The spending limits have doubled and most of that extra spend is going to go on digital, as you can’t actually spend it any other way. I don’t think anyone comprehends how much is going to be spent on advertising in this election,” he said.

Smaller political parties such as the Liberal Democrats, who are unlikely to raise the maximum £35m, are already concerned they could be squeezed out as voters are swamped with paid-for adverts – and left relying on the handful of free party political broadcasts that are given to all parties.

The media regulator Ofcom confirmed there was no legal ban on political campaigns buying adverts on video streaming services, meaning it is up to the individual streamers and broadcasters to choose their own policies.

This poses a challenge for companies such as ITV: either they take advantage of the streaming political advertising loophole and potentially earn substantial payments from parties, or they leave the cash on the table – and watch as YouTube, Instagram and Facebook take the money.

ITV, which is struggling with the wider downturn in television advertisers, said it would only run adverts that were fully compliant with all rules.

A spokesperson said: “Political advertising is prohibited on live television (including live simulcast channels within ITVX) but there are no such rules for streaming services such as ITVX more broadly or for video-sharing platforms such as YouTube, or social media networks such as Facebook.

“It is for political parties to consider where they wish to run their campaigns. As a commercial PSB [public service broadcaster], we’re considering our position on this issue very carefully.”

One consideration is the high trust that the British public still have for traditional television broadcasters – and whether that would be hurt by taking political adverts. Channel 4 continues to apply its political advert ban to its streaming service, while Sky said it would not be accepting political adverts on its Now TV streaming service. The US-owned streaming companies Netflix and Amazon Prime Video already have global bans on political adverts.

The last time the UK’s political ad ban was challenged was in 2013, when the European court of human rights narrowly upheld the UK’s policy and said it did not unduly compromise freedom of expression.

At the time, the then Conservative culture secretary, Maria Miller, celebrated the court’s decision, saying it “ensures the political views broadcast into our homes are not determined by those with the deepest pockets”.

A decade later, rapid changes in technology and viewing habits mean this approach is increasingly impossible to maintain.

• This article was amended on 14 April 2024. Commercial TV in the UK began in 1955, not 1954 as an earlier version said.