Air passengers braced for further delays on Tuesday after warnings that a 'new ash cloud' was heading towards Britain, hours after European officials agreed to let air traffic resume on a limited basis.
European Union transport ministers who met on a video link on Monday reached a deal to resume some flight operations, dividing northern European skies into three zones -- a 'no-fly' zone, a caution zone and a open zone.
However, Britain's Air traffic control company Nats said the 'situation was worsening' in some areas after the eruption of the Icelandic volcano strengthened.
But it said Scottish airports should be available from 7 am today (11.30 IST) and other airspace over England from 1 pm, although that does not include the main London airports.
The go-ahead for flights came as airlines pointed to successful test flights through closed airspace as a reason for lifting restrictions.
"The volcano eruption in Iceland has strengthened and a new ash cloud is spreading south and east towards the UK," Nats said.
"Latest information from the Met Office shows that the situation is worsening in some areas. . . This demonstrates the dynamic and rapidly changing conditions in which we are working," it said.
It said based on the fresh warning, the situation for Northern Irish airports was uncertain due to the new ash cloud.
Earlier, British Prime Minister Gordon Brown deployed two Royal Navy ships to help bring Britons home, with a third vessel also possibly being deployed.
The travel chaos also forced a leading Indian Book Store to cancel its exhibitions in London as flights were grounded at Heathrow and other airports in the UK.
Flipkart.com, largest online bookstore in India, cancelled its participation at the London Book Fair 2010 on Monday night as its chief operating officer Binny Bansal could not reach London from Bengaluru.
It was the only Indian online book store to have participated in the prestigious exhibition. Some European airlines meanwhile resumed operations bringing relief to thousands of passengers.
Three KLM passenger planes left Schiphol airport in Amsterdam under visual flight rules bound for New York, Dubai and Shanghai.
Britain's National Air Traffic Service said Scotland's airports and airspace would reopen at 2 a m (1130 IST) today and London's airports -- including Heathrow, Europe's busiest -- might be able to reopen later in the day.
The airlines said test flights in recent days by airlines including KLM, Lufthansa and British Airways suggested planes can fly safely despite the ash.
None of the flights reported problems or damage. Eurocontrol, the air traffic agency in Brussels, said less than one-third of flights in Europe took off on Monday, between 8,000 and 9,000 of the continent's 28,000 scheduled flights.
Officials said more are expected to operate on Tuesday.
