LOS LLANOS DE ADRIANE (AFP) - Spain on Monday (Dec 13) ordered more than 30,000 people to remain indoors on La Palma island for several hours because of toxic gases from a volcano that has been erupting for months.

After several days of low-level activity, the Cumbre Viejo suddenly sprang to life on Sunday with several explosions sending a vast cloud of ash and smoke into the sky.

The regional government of the Canary Islands, which lie off Africa's northwest coast, on Monday morning ordered residents of three municipalities to lock down owing to high levels of sulphur dioxide in the air.

But shortly after 2 pm (1400 GMT) it lifted the order due to "the improvement in air quality".

The three municipalities are home to roughly 33,000 people, or 38 percent of the population of the island, according to national statistics institute INE.

The regional government told residents to close windows and doors and seal them with tape to prevent air from coming in from the outside.

"Confine yourself, if possible, in the rooms located furthest inside," it added in a statement.

More than 7,000 people have been evacuated from their homes since the volcano erupted on September 19, spewing out rivers of red-hot lava that have slowly crept towards the sea.

Nobody has died as a result of the eruptions, but more than 2,800 buildings have been destroyed, according to EU monitoring service Copernicus.

This is La Palma's longest eruption and the third in a century, with previous ones in 1949 and 1971.