Britain's National Air Traffic Service said the UK airports were closed as the high density of the ash cloud drifted further south in the early hours of Monday.
Al Jazeera's Jonah Hull, reporting from Heathrow, said that ash cloud was disrupting landing aircraft, but most air traffic was returning to normal. "London's airports are operating relatively normally, albeit with some restrictions," he said.
European airspace was almost entirely shut down for nearly a week last month, after the Eyjafjallajokull volcano erupted and threw up an ash cloud over most of the continent.
The move led to the cancellation of some 100,000 flights, left millions of passengers stranded and cost airlines an estimated $1.7bn in losses, according to the International Air Transport Association.
The authorities reopened some airspace and airports after emergency talks between European governments, airlines and regulators resulted in a plan that divided the continent into safe and unsafe areas.
Airlines have criticised the latest restrictions, saying they are overly cautious.
"The closing of Manchester airspace once again is beyond a joke," Richard Branson, the president of Virgin Atlantic, said in a statement.
|The ash cloud has been wreaking havoc on European air travel since last month [AFP]
He said test flights have "shown no evidence that airlines could not continue to fly completely safely".
British Airways said that the approach was "overly restrictive and not justified on safety grounds".
Jonathan Nicholson, a spokesman for Britain's civil aviation authority, called Branson's remarks "surprising" after a meeting last week in which airline representatives and engine manufacturers agreed to find a way to ensure planes could fly safely in the volcanic ash.
"We as an organisation can't just say, 'Oh, I'm sure it's all right, go fly', without evidence it's safe," he said.
Areas in the latest no-fly zone include Heathrow, Gatwick and London City, as well as all airfields in Northern Ireland and airports in parts of Scotland, Nats said.
Teeside, Leeds-Bradford, Blackpool, Sheffield, Manchester, Liverpool, Doncaster, Carlisle, Humberside and East Midlands airports were already within the no-fly zone, Nats said, and airports in the Isle of Man were also affected.
The Irish Aviation Authority said three northwestern airports were closed from early Sunday and Dublin would be shut until 11:00 GMT on Wednesday.
Train operators Eurostar and Virgin Trains said they were adding more than 10,000 seats to their services in view of the air-travel disruption.
The volcano under the Eyjafjallajokull glacier in Iceland is continuing to erupt with no signs that the activity will end anytime soon.