It is now illegal in Japan to engage in stealth marketing with disguised advertisements.

The country's Consumer Affairs Agency has banned the practice under the law against unjustifiable premiums and misleading representation. The regulation takes effect from Sunday.

Stealth marketing involves covert promotions and advertisements.

The number of cases involving stealth marketing on social media has increased recently.

Influencers are asked by businesses to recommend their products, and do so by pretending not to have any relationship with the firms.

The new regulation covers all media, including the internet, newspapers and television.

It requires advertisements to clearly display words such as "ad" or "promotion" to differentiate them from stealth marketing.

When regulators identify violations, they can ban an advertisement, or order that actions be taken to prevent recurrences.