Live video images showed glowing lava oozing out of a fissure illuminating a plume of smoke rising up under the night sky.

"At 5:30 this morning intense small earthquake activity began northeast of Sylingarfell. About 30 minutes later, an eruption began in the same area," the Icelandic Meteorological Office (IMO) said in a statement.

IMO added that based on an initial assessment from a flyover by the Coast Guard, the fissure was about three kilometres (1.86 miles) long.

It occurred in the same area as two previous eruptions -- the first on December 18 and the second on January 14 -- near the fishing village Grindavik, which had been evacuated.

Iceland is home to over 30 active volcano systems, the highest number in Europe.

It straddles the Mid-Atlantic Ridge, a crack in the ocean floor separating the Eurasian and North American tectonic plates.

Until March 2021, the Reykjanes peninsula had not experienced an eruption for eight centuries.

Fresh eruptions occurred in August 2022, and July and December 2023, leading volcanologists to say it was probably the start of a new era of activity in the region.