The Government has issued a "smog alert" with potentially dangerous levels of air pollution predicted in England and Wales as thousands headed off for an Easter getaway.

Warm and still conditions brought on by the current high pressure system means levels of ozone and polluting particles known as PM10s, which can affect people's health, are expected to increase.

The Department for Environment, Food and Rural Affairs said some people, including those who have asthma, could be affected by the high pollution levels and may notice an effect on their breathing. It urged the public to take "sensible precautions" such as avoiding outdoor exercise and unnecessary short car journeys.

The warning comes as as the double Bank Holiday getaway gets into full swing, with millions of Britons flocking to destinations both at home and abroad. The late Easter and the royal wedding have resulted in employees having to take only three days off next week in order to to get an 11-day break, before returning to work on Tuesday May 3.

Those staying in the UK can expect more warm and sunny weather over the Easter weekend, with temperatures in London and south-east England likely to reach as high as 27C (81F) on Saturday.

Around two million people flocked abroad on Thursday, but those travelling to European hotspots were likely to see comparatively low temperatures. Malaga in southern Spain and the Greek Island of Corfu are only likely to reach around 17C (63F) on Friday and Barcelona only getting up to 16C (61F).

Motorists holidaying in the UK began to take to the roads on Thursday, with a number of disruptions reported. But the AA warned that "the worst is probably yet to come" as many people were yet to start their getaways.

The Highways Agency also suspended roadworks at a number of sites on England's motorways and major roads, but restrictions are still in place at some sites, including some on the M1 and M25.

The Association of Train Operating Companies said 1.8 million train journeys were expect to take place on Good Friday, with two million on Easter Saturday, 900,000 on Easter Sunday and 1.5 million on Easter Monday.

Network Rail said there would be some engineering work on the railways over Easter but that 18% more trains were running this holiday compared with last Easter. Disrupted services due to engineering include those using the West Coast line in north west England, services in and out of London's Liverpool Street station and trains on the Great Western line.