Air traffic to and from European destinations was disrupted by a cloud of volcanic ash from Iceland for a second consecutive day Sunday.

The cloud is lingering over northwestern Scotland and a finger stretches into the airspace over northwestern Spain and Portugal.

An isolated cloud is affecting southern France and northern Switzerland, while another hangs over southern Switzerland, northern Italy, southern Germany, the Czech Republic and Austria.

Roughly 1,000 fewer flights took place in European airspace on Sunday, a drop of four per cent from the usual number for this time of year.

Hundreds of flights were cancelled Saturday as plumes of ash again blew toward western Europe.

Spain closed 19 airports, while dozens of flights were also cancelled in Portugal.

Air traffic controllers say transatlantic flights are being diverted north over Greenland to avoid the ash cloud, which stretches from Iceland to the Azores.

Officials with Eurocontrol, the European flight control agency, warn the ash could spread during the coming days.

Volcanic activity in Iceland has closed parts of Europe's airspace on and off for more than a month.

In mid-April, the ash forced airlines to ground more than 100,000 flights and left as many as 10 million passengers stranded for days.

Volcanic ash can clog jet engines, causing them to stall.

Gritty ash has been spewing from a volcano in Iceland's Eyjafjallajokull glacier since April 13, following its first eruption in late March. Disruption of air travel occurs when wind currents blow the airborne ash into international flight lanes at altitudes where passenger aircraft fly.

The Eyjafjallajokull volcano last erupted from 1821 to 1823.