"The volcanic ash cloud from Iceland is moving around and changing shape," the National Air Traffic Services said in a statement yesterday.
Based on information from the Met Office, Britain's national weather service, "NATS advises that the restrictions currently in place across UK controlled airspace will remain in place until at least 1830 IST tomorrow.
"We will continue to monitor Met Office information and review our arrangements in line with that," it said.
The Met Office said it had detected evidence of ash dust over Britain and had reports of it reaching the ground.
"We continue to look for weather windows that will allow air space restrictions to be lifted," it said.
A research flight Friday found "three distinct layers of ash, from fine particles at low levels to large particles around 8,000 feet," it said.
"All these observations are consistent with our forecast plumes for where the ash cloud would spread and how it would mix through the atmosphere."
Published 18 April 2010, 05:29 IST