Facebook's Instagram has agreed measures to crack down on hidden advertising by paid so-called influencers on its photo and video platform, Britain's Competition and Markets Authority (CMA) said on Friday.
Influencers with thousands of followers can earn large fees from companies to promote a product on Instagram.
In what the CMA described as an important behaviour shift by a major social media platform, Facebook Ireland, which operates Instagram in Britain, has committed to a package of changes.
"This will make it much harder for people to post an advert on Instagram without labelling it as such," the CMA said in a statement.
The watchdog said it has been investigating concerns that too many influencers are posting content about businesses without making it clear they have been paid or received other incentives to do so.
Influencers will have to confirm and disclose if they have received any incentives to promote a product or service.
Instagram will also use technology to spot when users might not have disclosed clearly that a post is an advertisement, the CMA said.
Last year, 16 celebrities pledged to clean up their act on social media after CMA action, the watchdog said.