Spain's Secretary of State for EU Affairs Diego Lopez Garrido told reporters after a meeting at European aviation control agency Eurocontrol the ash cloud was moving slightly to the northeast, which could free up half of European air space.
"The forecast is that there will be half of flights possibly operating tomorrow. It will be difficult; that's why we have to coordinate," he said. European Union Transport Commissioner Siim Kallas also told the same briefing he hoped that 50% of European airspace would be risk free on Monday.
Kallas said the current situation was "not sustainable" and European authorities were working to find a solution that did not compromise safety.
"We cannot wait until the ash flows just disappear," he said.
Garrido said test flights had shown no damage to aircraft from the ash cloud.
"Lufthansa made 11 flights, KLM nine, Air France seven and the results show no impact in the area [...] no impact coming from the ash cloud," he said.
Kallas said a technical meeting of EU transport ministers on Monday afternoon would assess information from the test flights conducted in European countries.
"Based on new information from the test flights yesterday and today, we may be able to make a decision," he said. "All these new elements should be taken into account in the technical meeting."
He stressed the importance of a coordinated European response. "We have to deliver a more accurate European solution to open progressively European air space," he said.
Airlines and airport question safety measures
Earlier, the main associations of European airports and airlines questioned the proportionality of restrictions that have closed much of European airspace and called for a reassessment.
"While Europe's airlines and airports consider safety to be an absolute priority, they are questioning the proportionality of the flight restrictions currently imposed," ACI Europe said in a statement.
The European aviation control agency Eurocontrol said about 5,000 flights took place in European airspace on Sunday compared with 24,000 normally.
In Belgium, airspace will remain closed until at least 0600 GMT on Monday, said a spokesman for Transport Minister Etienne Schouppe.
EU to assess economic impact
Meanwhile, the European Commission said on Sunday it was setting up a group to assess the economic impact of the volcanic ash cloud from Iceland and said any steps taken across the European Union needed to be properly coordinated.
"The volcanic ash cloud has created an unprecedented situation," European Commission President José Manuel Barroso said in a statement.
"I have asked [EU Transport Commissioner Siim] Kallas to coordinate the Commission's response and fully assess the impact of the situation created by the volcanic ash cloud on the economy, and the air travel industry in particular.
"It is important that all measures to be considered are coordinated at the European level."
Barroso said Kallas would be helped by Competition and State Aid Commissioner Joaquin Almunia and Economic and Monetary Affairs Commissioner Olli Rehn.
EU ministers teleconference meeting
A spokeswoman for the Spanish EU Presidency said Spain would preside over a meeting by tele- and videoconference of EU transport ministers on Monday to discuss the crisis caused by the ash cloud and possible measures in response to it.
Earlier, the Spanish EU Presidency said other EU ministerial meetings due to be held on Monday had been postponed because of flight cancellations caused by the spread of volcanic ash.
These included meetings of EU agriculture and fisheries ministers due to be held in Luxembourg and a conference between the EU and Croatia on the latter's EU accession bid due to have been held in Brussels, the presidency said.
A meeting of EU telecommunications ministers in Granada on Monday will go ahead, the presidency said in a statement.
(EurActiv with Reuters.)
