People on parts of the coast of La Palma have been ordered to stay indoors amid concern that lava from an erupting volcano could trigger toxic gases and explosions as it reaches the sea.
Clouds of white steam were seen rising as a red-hot current made contact with the water in the Playa Nueva area on the Canary island.
This could trigger a chemical reaction, involving chlorine, which can irritate the skin and eyes and affect breathing.
A red alert remains in force, and in the Tazacorte districts, near the west coast – which have been affected by heavy ash fall – the public have been advised to remain indoors.
Hundreds of homes have been destroyed since the Cumbre Vieja volcano erupted on September 19.
About 6,000 people have been evacuated, as the lava was engulfing houses, schools and some banana plantations.
Three coastal villages were earlier locked down in anticipation of the lava making contact with the water.
Spanish authorities have declared La Palma – the most north-westerly island of the archipelago – a disaster zone, pledging financial support for all those affected by the volcanic activity.
Around 200 people evacuated last Friday have been allowed to return to their houses in three villages but the 5,600 evacuated on the first day remain out of their homes as a precaution as two lava flows remain active, island authorities confirmed.
Three hundred coastal residents have been ordered to remain indoors “given the possibility that the lava might reach the sea and trigger explosions and vapourisations”.
A ‘no sailing’ order has been extended “in view of the increased possibility that the lava will come into contact with the sea”.
A spokesman stressed that gas clouds of this kind dilute rapidly and the ‘stay indoors’ measure had been ordered as a precaution. However, two lava flows remain active.
Julio Perez, the minister responsible for the region’s volcano emergencies plan, said that the current operation to ensure the safety of the population of La Palma will continue for as long as the eruption lasts.
“We are working as one administration in this crisis,” he said.
Airlines continue to suspend flights to and from the island despite La Palma airport reopening.