Iceland’s weather service says an eruption of molten rock from the magma tunnel in the southwest of the country is likely in the coming days, after weeks of seismic activity there.

This is the most likely scenario, the head of the volcano department at the weather service Kristín Jónsdóttir told RUV radio station on Friday.

Geophysicist Benedikt Ófeigsson said that there were clear signs that the magma tunnel under the Reykjanes Peninsula was expanding.

The weather service registered about 1000 earthquakes on Friday since midnight.

The deformation of the ground is progressing but has slowed down somewhat, RUV reported.

Gas indicating magma was measured near the Svartsengi power plant north of the evacuated town of Grindavík.

Grindavík, located about 40km southwest of the capital Reykjavik, has been on alert amid the threat of an eruption for days.

About 3700 inhabitants were relocated a week ago because a magma tunnel about 15km-long runs under Grindavík to below the seabed.

The activity has also led to the closure of the nearby Blue Lagoon, one of Iceland’s most famous tourist attractions.

—AAP