Air traffic over southern Europe faces more disruptions on Tuesday from a cloud of ash drifting in off the Atlantic from the Icelandic volcano Eyjafjallajokull, just as Pope Benedict begins a visit to Portugal.

Even as clearer skies in some areas allowed flights to resume after a weekend of cancellations across southern and central Europe, a change in wind direction has now forced Spain to again close down operations at four airports in the Canary Islands and three others on the southern mainland.

Both airports on Tenerife, plus those on La Palma and La Gomera, suspended air traffic early Tuesday morning, while the airports in Seville, Jerez and Badajoz shut down a short time later.

A spokesman for AENA, the Spanish aviation control agency, said it was not known when they could re-open.

For the first time, too, the ash has spread further south and eastward, closing airports in northern Morocco and western Turkey.

About 500 fewer flights took off across Europe on Monday because of the ash cloud, which continues to force transtlantic flights to and from North America to fly lengthy detours around it.

The AENA spokesman said that some air corridors normally reserved for the military may now be used for civil aviation.

Ash could crimp papal visit

In neighboring Portugal, airports in Lisbon and Porto re-opened on Monday, but Faro was closed later in the evening as the ash cloud swept across the country's southern Algarve region. More closures could come on Tuesday.

Lisbon is the arrival point for Pope Benedict XVI, who begins a four-day visit to Portugal on Tuesday. But Catholic Church officials said that, if necessary, there was a 'plan B' to ensure the pontiff's trip goes ahead as scheduled.

Geologists in Iceland say that while the situation should improve over the next few days, the volcanic eruption is not about to end anytime soon.

gb/dpa/AFP/Reuters
Editor: Nancy Isenson