A "rapidly encroaching" volcanic ash cloud has forced part of Britain's skies to close and cause another round of flight disruption.

Air traffic chiefs have imposed a no-fly zone above parts of Northern Ireland after the "high density" cloud approached the province from the north west.

Flights to and from Belfast International and Belfast City airports, and Ronaldsway airport on the Isle of Man have been cancelled until at least 1pm on Sunday.

There are also restrictions on airfields in north west Ireland, air traffic controllers said, but Dublin Airport remains open. No other parts of UK airspace are currently affected.

The Department of Transport has warned about possible flight disruption elsewhere across the UK, lasting perhaps until Tuesday morning, if the ash from the erupting Icelandic volcano Eyjafjallajokull is blown above Britain.

It is bad news for passengers hoping the skies were getting back to normal a month after ash from the eruption first cancelled a swathe of flights across Europe.

The cloud is expected to lie over the London area by Tuesday, but is likely to have drifted out of UK airspace by Wednesday, according to forecasters.

In a statement, the air traffic authority Nats said: "A high density volcanic ash cloud is rapidly encroaching on Northern Ireland and the Isle of Man.

"As a result, a no-fly zone has been imposed by the Civil Aviation Authority in airspace over parts of Northern Ireland.

"There are currently no other restrictions within UK airspace."