They seem to be selling a deadly chemical, and have no qualms about offering it to people who may be at risk of suicide. But is their business what it seems - or just an elaborate scam?

A Trending investigation has uncovered dozens of pages claiming to sell a highly toxic substance that, in many countries, cannot be bought without a licence.

While the substance has some industrial uses, the supposed sellers running these pages have their eyes on a different type of customer: someone looking online for a way to take their own life.

Facebook says it won’t allow content on their platform that encourages suicide – yet some of these pages have been running for several years.

Experts say they are a scam – but how exactly does it work? We went undercover to investigate the shadowy pages peddling deadly poison.

If you are affected by the issues in this programme, you can find information about support organisations on the Befrienders Worldwide website: https://www.befrienders.org/

Presenter: Marco Silva

(Photo caption: illustration of a smartphone showing a bottle of poison containing Facebook logos/ Photo credit: BBC)