Thousands fleed their homes and flights were grounded as Chilean volcano sends plumes of ash showering down. The Chilean volcano which erupted in July 2011 has sent a towering plume of ash across South America, forcing thousands from their homes, grounding airline flights in southern Argentina and coating ski resorts with a gritty layer of dust instead of snow.

Booming explosions echoed across the Andes as toxic gases belched up from a three-mile-long fissure in the Puyehue-Cordon Caulle volcanic complex - a ridge between two craters just west of the Chilean-Argentine border that began erupting Saturday.

Winds blew a six-mile high cloud of ash all the way to the Atlantic Ocean and even into southern Buenos Aires province, hundreds of miles to the north-east.

Authorities in Chile went house to house, trying to persuade stragglers near the volcano to evacuate because of an increasing danger of toxic gas and flash floods. Winds fanned the ash toward neighbouring Argentina, darkening the sky in the ski resort city of San Carlos de Bariloche, in the centre of the country, and its airport has also been closed. The eruption in the Puyehue-Cordon Caulle volcanic chain, about 575 miles south of the capital, Santiago, also prompted authorities to close a busy border crossing into Argentina.  It was not immediately clear which of the chain's four volcanoes had erupted because of ash cover and weather conditions. The chain last saw a major eruption in 1960

Local media said the smell of sulphur hung in the air and there was constant seismic activity. 'The Cordon Caulle (volcanic range) has entered an eruptive process, with an explosion resulting in a 10-kilometre-high gas column,' the state emergency office ONEMI said.  As a precaution, the government said it was evacuating 3,500 people from the surrounding area.  This development is the latest volcanic activity to affect the country.  Three years ago, Chile's Chaiten volcano erupted spectacularly for the first time in thousands of years, spewing molten rock and a vast cloud of ash that reached the stratosphere and was visible from space. It also drifted over neighbouring Argentina, coating towns. Chile's Llaima volcano, one of South America's most active, also erupted that year and again in 2009.

An extraordinary cloud formation is created by the ash rising several miles into the atmosphere.  It was the latest in a series of volcanic eruptions in Chile in recent years.  Chile's Chaiten volcano erupted spectacularly in 2008 for the first time in thousands of years, spewing molten rock and a vast cloud of ash that reached the stratosphere. The ash also swelled a nearby river and ravaged a nearby town of the same name.  The ash cloud from Chaiten coated towns in Argentina and was visible from space.  Chile's Llaima volcano, one of South America's most active, erupted in 2008 and 2009.  Chile's chain of about 2,000 volcanoes is the world's second largest after Indonesia.  Some 50 to 60 are on record as having erupted, and 500 are potentially active.