Iceland has raised the aviation alert at its largest volcano, Bardarbunga, to maximum level red following a new eruption in a lava field nearby.
The alert entails a ban on all flights below 6,000 feet (1.8 kilometres) within a radius of 10 nautical miles (18.5 kilometres) of Bardarbunga.
"All airports are open. The area has no effect on any airports," the Civil Protection Office said in a statement.
Sunday was the third time in a week that Iceland issued a red alert for aviation due to seismic activity at the peak, prompting fears of global flight chaos like that caused by another Icelandic volcano four years earlier.
In April 2010 Eyjafjoell, a smaller volcano, spewed a massive ash cloud into the atmosphere, triggering the closure of airspace for days and stranding more than eight million travellers.
Bardarbunga, at 2,000 metres (6,500 feet), is Iceland's second-highest peak and is located under Europe's largest glacier, Vatnajoekull.
It also sits in one of the most active seismic areas on the planet.
The Bardarbunga volcano system, in the southeast of the country, became active on August 16, producing hundreds of tremors daily.
Sunday's eruption took place shortly before 0600 GMT in roughly the same area in Holuhraun lava field where another and smaller eruption took place Friday, according to the Civil Protection Office.
And it took place along a longer fissure than Friday's eruption -- 1.5-kilometre compared with one-kilometre =.
The authorities also said that scientists who had been monitoring the eruption were forced to flee on Sunday because a sandstorm was sweeping across the Bardarbunga area.
The Vatnajoekull glacier which covers the volcano is largely uninhabited but popular with tourists and hunters, who stay at trekking cabins and campsites in the summer months. The area was evacuated within days of Bardarbunga kicking into action.