The consumer goods company has pledged never to use influencers who buy followers to advertise its brands, which include Marmite, Dove soap and Colman's Mustard.

They also warn of the limited ways of accurately tracking the benefits of promotion from social media stars and measuring "authentic engagement".

Zazzle Media, a UK-based marketer, said the appeal of influencers is falling and they are "not a key focus" for any of the brands they work with.

A survey of brands done by the company found that influencers were not a focus for a single one.

"Part of the problem is it's hard to determine return on investment with influencers", said Julia Ogden, Content and PR Director for the company.

"Some do it for free, they're happy to do whatever for an incentive. Some are charging a couple of hundred pounds, some tens of thousands. It's even more when they have an agent."