Smoke billows from an erupting volcano on the Eyjafjallajokull glacier on April 14. (AFP)

REYKJAVIK (AFP) – There was no sign of escalating activity at Iceland's erupting volcano Tuesday, and the plume of ash wreaking havoc  for air traffic across Europe had clearly diminished, experts said.

"We are not seeing an escalation in activity," University of Iceland geophysicist Sigrun Hreinsdottir told AFP.

"We still see a contraction of the volcano, which is always good. I would worry if we saw expansion of the volcano, but we are seeing the volcano shrink," she added.

She said she was "really surprised" that Britain's National Air Traffic Services (NATS) said late Monday that the eruption was increasing and a new ash cloud was heading towards the British isles.

Gudrun Nina Petersen of the Icelandic Meteorological Office meanwhile said the volcano was clearly spewing less ash.

"If there (is) ash detected over England tonight that's going to be from 24 hours earlier," she said.