A firefighting operation will continue into the night to quell a blaze which began on Sunday and has affected one square kilometre (250 acres) of the New Forest national park in Hampshire.

It began when a van caught fire on the A31 near Bratley Wood, forcing motorists to abandon more than 20 vehicles.

Lindsey Legg was with her husband and three children when they were forced to stop by police and leave their car. She said “women and children were walking with buggies” on the road and it had been “pretty scary”.

National Highways said the A31 dual carriageway through the New Forest would remain closed in both directions until further notice.

Hampshire and Isle of Wight Fire and Rescue Service said more than 120 firefighters had been working “in challenging conditions” to contain the blaze.

Forestry England said the blaze was under control, but it expected the firefighting operation to continue for several days.

It said it was supporting the fire service with car park closures to make sure it had easy access to the area.

Spokeswoman Esta Mion added: “There are still flames on site… but it is under control.

“It’s nowhere near as bad as it was at the height of the fire last night. But we are very much asking people to stay away… it’s unpredictable.”

The blaze was started by a van fire on the A31 which spread to Bratley Wood and the surrounding area, Forestry England confirmed.

Aerial footage of scorched vegetation showed how the fire funnelled outwards in a south-easterly direction as the wind fanned the flames.

Smoke from the blaze drifted across both sides of the Solent, prompting fire crews to urge people to keep doors and windows shut.

The fire service said an 8km (5-mile) hose had been laid from Hightown Lake, just east of Ringwood, to supply water to crews tackling the blaze.

In some areas, the hose crosses tracks and passes through private property and residents were urged not to drive over it to avoid causing damage.

Legg, who was travelling back to Bournemouth from Heathrow, told BBC Radio Solent: “We started seeing people abandoning their cars. Women and children were walking with buggies.

“Police told us ‘you can’t go any further’. We realised the fire was going through the field – it was pretty scary.

“We had to abandon the car and cross the central reservation to get away from the side of the fire. We thought the car was going to go up at one point.”

New Forest National Park Authority said the impact on the forest ecosystem and rare species would be severe.

“It’s rare heathland, which globally is more rare than rainforest,” a spokesperson said.

“We have the highest concentration of lowland heathland in western Europe and it’s internationally protected.

“It is home to all six UK native reptiles, Dartford warblers, nightjars, insects – it’s devastating.”

Police said the 23 vehicles left behind by motorists were moved so they could be collected by the owners later.

National Highways said there was significant damage to the road surface and crash barrier following the fire and oil spillage from the burnt out vehicle.

It said there was no estimated time for reopening the road, which is a main tourist route to Dorset and south-west England.