Chile has declared a red alert around the Llaima volcano, just days after it spewed lava down one of its sides.

Llaima is considered one of South America's most active volcanoes.

The 3,125m snow-capped volcano located 700km south of the Chile's capital Santiago, affected a lightly populated area on the slopes of Llama that is home to at least 40 people from the Vilcun village.

"There is renewed activity as lava is flowing towards the Calbuco River," Juan Cayupi, a volcanologist at the state National Emergency Office said.

"[The lava] has reached around 800 to 1,000m from the crater," he said.

Llama last erupted on New Year's day, forcing the evacuation of some tourists and residents from surrounding areas.

It then belched ash and lava in February.

Llaima's renewed activity comes after the Chaiten volcano, at least 1,220km south of Santiago, started erupting on May 2 for the first time in thousands of years, spewing out ash, gas and molten rock.

Chile's chain of some 2,000 volcanoes is the world's second-largest after Indonesia's.

At least 50 volcanoes are recorded to have erupted, while a total of 500 are deemed potentially active.