Aviation industry slams closures
The aviation industry has condemned European transport officials, claiming there has been "no co-ordination and no leadership" in the crisis that has shut down most European airports for a fifth day.
Eurocontrol, the air traffic agency in Brussels, said less than one third of flights in Europe were taking off on Monday - between 8,000 and 9,000 of the continent's 28,000 scheduled flights.
Some smaller airports reopened but authorities in Britain, France, Germany and the Netherlands - home to four of Europe's five largest airports - said their airspace was still closed.
Britain said it was keeping flight restrictions in place until early Tuesday, while Italy briefly lifted restrictions in the north but then quickly closed down again after conditions worsened.
The International Air Transport Association (IATA) says the airport lockdowns are costing the aviation industry at least $200m a day.
Millions of travellers have been stranded since the volcano under Iceland's Eyjafjallajokull glacier begun erupting on Wednesday for the second time in a month.
Meeting in Paris, the IATA expressed its "dissatisfaction with how governments have managed it, with no risk assessment, no consultation, no co-ordination and no leadership", and called for greater urgency in reopening Europe's skies.
Several major airlines safely tested the skies with weekend flights that did not carry passengers.
The announcement of successful test flights prompted some airline officials to question whether authorities had overreacted to concerns that the microscopic particles of volcanic ash could cause jet engines to fail.
Transport ministers from Britain, Germany, France and Spain were meeting via video-conference and will later be joined by all 27 EU transport ministers, said French transport minister Dominique Bussereau.
"We will try to outline corridors, if we can, based on the evolution of the cloud, to allow the reopening of as large a number of flight paths as possible, as quickly as possible and in good security conditions," Bussereau said.
Eurocontrol said that southern Europe, including Portugal, Spain, parts of Italy and France, the Balkans, Bulgaria, Greece and Turkey, and parts of northern Europe were currently open for flights.