Iceland closed its main international airport Sunday after the country's most active volcano, Grimsvotn, sent ash and smoke 20 kilometres into the air.

Ash was expected to spread over Iceland over several hours, shutting Keflavik and other airports on the island.

However, the plume was not heading toward Europe, Iceland's Meteorological Office said. The ash was instead blowing west toward Greenland.

The Grimsvotn volcano, which lies under the uninhabited Vatnajokull glacier, began erupting Saturday for the first time since 2004.

But officials say it is unlikey to have the same impact as last spring's eruption of the Eyjafjallajokull volcano, which forced the closure of a large section of European airspace.

Officials closed the continent's air space for five days in April 2010, fearing the ash could damage jet engines. Some 10 million travellers were stranded.

Icelandic air traffic control operator ISAVIA established a 120 nautical mile (220 kilometre) no-fly zone around the volcano, closed Keflavik airport, the country's main hub, and cancelled all domestic flights. It said Keflavik would stay shut until at least noon Monday, cancelling about 40 international flights.

The European air traffic control agency in Brussels said there was no impact on European or trans-Atlantic flights further south and said it did not anticipate any impact through Monday.

Winds not as strong, ash falling quickly

Britain's Meteorological Office, which runs Europe's Volcanic Ash Advisory Center, said the plume from the volcano would spread largely northeast until Monday, but some ash would creep south and east, toward the crowded skies over northern Europe.

Where it goes after that depends on the intensity of the eruption and weather patterns.

A Met Office spokeswoman said if the eruption continues at its current rate, "the U.K. could be at risk of seeing some volcanic ash later this week."

University of Iceland geophysicist Magnus Tumi Gudmundsson said the Grimsvotn eruption was "much bigger and more intensive" than last year's eruption and 10 times as powerful as Grimsvotn's last explosion in 2004.

"There is a very large area in southeast Iceland where there is almost total darkness and heavy fall of ash," he said. "But it is not spreading nearly as much. The winds are not as strong as they were [last year]."

He said the ash now is coarser than in last year's eruption, falling to the ground more quickly.

Grimsvotn's eruption in 2004 lasted for several days and briefly disrupted international flights. The volcano also erupted in 1998, 1996 and 1993.

With files from The Associated Press