Iceland has put its aviation warning level at red after lava was spotted spewing out of a fissure near the Bardarbunga volcano.
The level was briefly lowered to orange over the weekend but Iceland's Met Office raised it back to a red on Sunday.
Colour code red is the highest level and indicates "eruption is imminent or in progress - significant emission of ash into atmosphere likely".
The red alert meant that no flights are allowed in an airspace area of about 40 square nautical miles north of the fissure eruption area, up to 6,000 feet (1.1 miles) from the ground.
According to the Daily Mail, restrictions currently do not affect commercial flights, which fly at 35,000ft.
Sunday's eruption in Holuhraun lava field area was described as "calm but continuous". Lava fountains about 50 metres high erupted from the fissure, which is almost a mile long.
The fissure eruption appeared about 28 miles from the main Bardarbunga volcano, which lies under the Vatnajokull glacier in the eastern corner of Iceland.
It happened in approximately the same place as an eruption on Friday morning, and is the third to happen in the area in a week.
However, according to the BBC, there was around 10 times more lava than Friday's eruption, said Armann Hoskuldssonk, a geologist from the University of Iceland.
Back in 2010, the Eyjafjallajokull volcano erupted spewing a massive cloud of ash that shut down much of Europe's airspace for six days causing travel chaos.
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