Deadly algae on French beaches 'releasing toxic fumes that can kill in seconds'

Fears over toxic algae - which experts say can kill within seconds - have led to the closure of six French beaches over the summer.

The algae can reportedly release toxic fumes when stepped on, causing unsuspecting visitors to lose consciousness and stop breathing.

At least three people and a large number of animals - including wild boars, dogs and a horse - have died after inhaling hydrogen sulfide released by the algae, according to news outlet France24.

In July, an 18-year-old oyster farmer and a 70-year-old pensioner died within the space of a week on two different beaches in Brittany.

Andre Ollivro, who has been leading the campaign to combat the silent killer, told France24: "These areas are like a mille-feuille that decomposes and turns into a minefield.

"Take one step, nothing happens. Take another, and you end up with 1,000 ppm (a fatal level of hydrogen sulfide)."

Mr Ollivro told The Guardian that the algae "could kill you in seconds", with concentrations of 500 to 700 parts per million (ppm) potentially fatal for an adult human if they are not quickly moved to fresher air.

A person can die within minutes with concentrations at 1,000 ppm.

Mr Ollivro claims the problem is the result of governments failing to reduce the amount of nitrates released by farms.

One of the worst-hit areas, the bay of Saint-Brieuc, had to close an inland treatment centre where seaweed was being processed after local residents complained of a foul stench.

The beach of Saint-Brieuc was also closed to the public by the town's mayor, while the owners of cabins along the bay have been barred from entering their properties.

Concerns have been raised about the dangerous algae since the 1970s.

Accusations of a public health scandal stepped up in 1989 when a jogger was found dead amongst seaweed on the beach at Saint-Michel-en-Greve.

An emergency doctor questioned his cause of death and complained the post-mortem results had not been made public.

Scientists say the algae's spread is linked to the agriculture industry in Brittany, including pig, cattle and poultry farming.

Nitrates and phosphates from animal waste and fertilisers enter the sea, causing harmful algal blooms.