Special Report: Iceland volcano eruption

Much of Europe remained virtually a no-fly zone on Monday though successful test flights have been conducted after volcanic ash from Iceland caused an airspace shutdown that has plunged EU meetings into chaos.

Passengers wait as flights restriction continues at Vienna International Airport in Vienna, Austria, April 17, 2010. [Liu Gang/Xinhua]

Several test flights were conducted by airline companies such as Air France and Germany's Lufthansa on Saturday to assess the air traffic conditions in the wake of Wednesday's volcanic eruption in Iceland.

Almost all the flights concluded without reporting major damage. But people are still cautious, and the prospects for a return to normal air travel remain far from clear.

Successful test flights do not mean that passenger flights will resume soon, head of the Royal Dutch Airlines KLM Peter Hartman said, adding the KLM will conduct more test flights to study the impact of volcanic ash clouds on aircraft.

Britain's flight restrictions will remain in place until at least 1800 GMT, air authorities confirmed Monday.

"Conditions around the movement of the layers of the volcanic ash cloud over the UK remain dynamic," the National Air Traffic Services (NATS) said in a statement, adding that they would update their assessment at around 0800 GMT.

Most French airports including international hubs Charles de Gaulle and Orly will stay closed until Tuesday morning.

Austria's air traffic controllers on Sunday decided to further extend the closure of Austrian airspace until 0400 GMT on Monday.

Meanwhile, the whole Danish airspace will remain closed until 1200 GMT on Monday. Switzerland also extended a ban on commercial flights at its airports until 1200 GMT on Monday.