Complaints about adverts on television increased by 43% last year, while influencer posts made up almost a quarter of all online cases, the regulator’s annual figures show.

Increased television viewing during lockdown could have been behind the sharp rise in complaints to 14,211 about 5,070 ads, but they still made up only one fifth of all cases, the Advertising Standards Authority (ASA) said.

In contrast, complaints about influencer posts still made up a quarter of online cases despite decreasing by 8% on the year before.

The ASA put influencers “on notice” after a monitoring sweep of more than 24,000 posts revealed the proportion of them sticking to the rules – in particular failing to make clear they were ads – was “far below what we would expect”.

The ASA and Committees of Advertising Practice (CAP) annual report shows the regulator resolved 36,342 complaints about 22,823 ads in 2020 and had a record 36,491 ads withdrawn or amended – an increase of 346% on 2019 thanks to its use of technology-assisted online ad monitoring.

Online cases made up 61% of all cases and nearly half of all complaints across media, or 17,379 complaints about 14,512 cases.

The health and beauty sector had the most ads amended and withdrawn, in large part due to compliance projects investigating campaigns for botox and IV drips.

Ryanair’s “Jab and Go” ad was the most complained about last year and became the third most complained about advert of all time after prompting 2,371 complaints.

The advert encouraged consumers to book Easter and summer holidays with the airline after having received vaccinations, suggesting that people could “jab and go”.

But the ASA said that due to the “complex and constantly evolving” situation, consumers could be “confused or uncertain” and it was important that advertisers were “cautious”.

ASA chief executive Guy Parker said: “Despite the huge challenges of the last 12 months, we doubled down on protecting children and people in vulnerable circumstances.

“We smashed our previous record of ads amended or withdrawn. We’re exploring holding online platforms to greater account for their role in upholding responsible ads online and we’re running important projects on the environment, racial and ethnic stereotyping and body image.

“In all of this, our increased use of technology is transforming the way we tackle harmful and misleading ads and helping us to better protect people.”