While some countries including France, Germany and Belgium did allow a gradual resumption of flights, others scrapped plans to end their lockdown as authorities in Iceland said the volcanic activity was still “considerable”.

Millions of people have been stranded across the globe since Europe began shutting down airspace six days ago, while the world association of airlines, IATA, says the crisis is costing the industry 200 million dollars a day.

Airlines such as British Airways and Germany’s Lufthansa have been at the forefront of pressure for an immediate reopening of the airspace and had hoped that Tuesday would mark the beginning of the end of the crisis.

However British Airways cancelled all its short-haul flights after the National Air Traffic Services, which manages the country’s airspace, said the situation was “worsening in some areas”.

“The volcano eruption in Iceland has strengthened and a new ash cloud is spreading south and east towards the UK,” NATS said in a statement.

In Iceland itself, police said blasts could be seen from three separate craters, although the plume of ash from the Eyjafjoell volcano was diminishing.

“There is still considerable volcanic activity at the site and three seemingly separate craters are still erupting,” a police statement said.

“The plume is still rising but it is smaller and lighter, indicating that there is not much ash in it.”

Eye-stinging, sulphuric dust enveloped farmland under the volcano while visibility fell to 50 metres (yards) and cars drove with headlights on during daylight.

The French-based European Volcanic Ash Advisory Centre (VAAC) said that the fresh ash would pass over Britain and Denmark but spare other parts of Europe.

While several smaller airports in Britain did resume operations, London Heathrow — Europe’s biggest — remained closed.

BA said it was “still hoping” to operate long-haul flights as planned from 1500 GMT Tuesday, “however this remains subject to the full and permanent opening of airspace”.

Budget airline easyJet said all its flights to and from northern Europe including Britain would be cancelled until 1600 GMT, but it would continue to operate routes in southern Europe.

Australia’s Qantas Airways extended its ban on flights to and from Europe for another 24 hours on Tuesday, citing “additional volcanic activity”.

Aviation authorities in Ireland had also hoped to reopen its airspace from 0400 GMT but announced the ban was being extended for at least another eight hours as a result of fresh spurts of ash.

Denmark’s aviation authority Naviair said all its airports would remain closed until at least Wednesday and Norway, which had reopened virtually all of its airspace Monday, announced the shutdown of airspace over its southwest.

German airspace was to remain closed until 2:00 pm (1200 GMT) although the national carrier Lufthansa was given special permission to fly visually rather than relying on instruments, and staying in constant contact with air traffic controllers.

Lufthansa said it planned to carry more than 15,000 passengers on some 200 flights on Tuesday, around 11 percent of its normal daily schedule.

Airspace over northern Italy slowly re-opened with the first flights leaving Rome and Milan. Flights also began landing at Belgian airports, including Brussels, although no departures would be allowed until the afternoon.

And in France, Transport Minister Dominique Bussereau said that 30 percent of scheduled national and international flights would fly from Paris’s main airports, Charles de Gaulle and Orly on Tuesday.

“I am happy, I’m going to see my wife again,” said an Ivorian man after stepping off a flight from Abidjan at Charles de Gaulle.

Others who made it back home after gruelling journeys overland expressed relief that their ordeal was over.

“We were supposed to fly back on Sunday,” said exhausted German housewife Adelheid Jung, one of about 700 stranded tourists brought back from Spain in special buses to Frankfurt overnight.

“We were lucky to get this bus, and then our son-in-law has come to pick us up in his car to take us home to Cologne,” she said, steeling herself for the 200-kilometre final stretch.

Even the world’s top footballers have been caught up in the chaos with Barcelona having to travel by bus to Milan for Tuesday night’s Champions League semi-final.

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