Iceland's most active volcano, Grimsvotn, has started erupting, scientists say.

The volcano, which lies under the Vatnajokull glacier in south-east Iceland, last erupted in 2004.

In 2010, plumes of ash from Iceland's Eyjafjallajokull volcano caused weeks of air travel chaos across Europe.

Scientists say the latest eruption is unlikely to cause similar problems, although it may trigger localised flooding.

Volcanic eruptions are common in Iceland, which lies along the Mid-Atlantic Ridge that divides the Eurasian and North American continental plates.

Icelandic Meteorological Office geologist Hjorleifur Sveinbjornsson told Reuters that Grimsvotn had thrown a plume of white smoke about 15km (nine miles) into the air.

"It can be a big eruption, but it is unlikely to be like last year," he added.

Last year's outpouring of ash from Eyjafjallajokull led to the largest closure of European airspace since World War II.

About 10 million travellers were affected and some questioned whether the shutdown was an over-reaction.

However, a scientific study published last month said the safety concerns had been well founded.

Researchers from the University of Copenhagen and the University of Iceland said ash particles from the early part of the Eyjafjallajokull eruption were especially abrasive, posing a possible threat to aircraft.

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The Icelandic authorities have imposed a local flight ban after the country's most active volcano, Grimsvotn, began erupting.

A plume of smoke has risen 20km (12 miles) into the sky from the volcano.

Flights in Scotland are cancelled by a regional airline as a volcanic ash cloud from Iceland continues to head towards the UK.

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Iceland's Grimsvötn volcano sends thousands of tonnes of volcanic ash into the sky after erupting on Sunday.