State of emergency declared: Lava shoots to the heavens; Emergency evacuation in progress VIDEO

A state of emergency has been declared, but air travel to and from Iceland is not expected to be affected.

A new fissure has opened near Sundhnukagigar on the Reykjanes peninsula, the fifth eruption in the area since December.

The Icelandic Meteorological Office (IMO) said the crack is more than 2.5 km long and continues to grow.

The mayor of Grindavík, Fannar Jonasson, told state broadcaster RUV that he was concerned about the amount of lava flowing towards the city, which was "much larger in volume" than seen after recent eruptions.

Energy distributor HS Veitur said electricity to Grindavík had been turned off as a precaution.

Three people refused to leave the city, local media reported. Officials issued a statement "for all those in or near Grindavík to leave the area and move to a safe distance."

All but one of the roads in and out of the city are now inaccessible.

Footage from the eruption site shows a wall of molten rock shooting up to 50 meters high, and a huge amount of ash covering much of the sky.

Keflavik International Airport said it was operating as usual and was not expected to be affected by the eruption.

Officials reported "intense earthquake activity" before Wednesday's eruption.

Geophysicist Ari Trausti Guðmundsson said scientists had been expecting a new eruption for some time. Most of Grindavík's 4,000 residents were permanently evacuated in November, before eruptions in December, January, February and March.

Iceland has 33 active volcanic systems and sits above what is known as the Mid-Atlantic Ridge, the boundary between the two largest tectonic plates on the planet.

This is the eighth eruption since 2021, and scientists believe the area is entering a new volcanic era that could last decades or even centuries.