Aviation authorities are watching for developments in Iceland, where planes are on high alert after a volcanic eruption.
The country has closed airspace directly above Bardarbunga volcano after it began erupting under the ice of Europe's largest glacier following thousands of earthquakes.
The UK's air traffic control organisation NATS and safety regulator the Civil Aviation Authority (CAA) say they are ready to take action if ash is detected. Continued exposure to concentrated levels of volcanic ash can lead to the total failure of aircraft engines. A Virgin Atlantic flight from London Heathrow to San Francisco was diverted away from the volcano on Saturday as a precaution.
A Virgin Atlantic flight from London Heathrow to San Francisco was diverted away from the volcano on Saturday as a precaution.
But flights are now operating normally, a spokesman for the airline said.
An eruption of the Eyjafjallajokull volcano in southern Iceland four years ago produced an ash cloud that led to a week of aviation chaos.
More than 100,000 flights were cancelled.
A spokeswoman for NATS said it was "monitoring the situation" and working with other agencies, including the Met Office and Civil Aviation Authority.
NATS will help determine what impact the eruption will have on UK airspace and advise airline customers accordingly, she added.