The first minister of Scotland has asked for military aid from the UK government as more than 500 firefighters continue to tackle a fire that has raged in the Cairngorms national park for the past 10 days and forced the evacuation of homes in the remote region.

John Swinney has said the blaze remains a “major and serious” incident but that Saturday afternoon had brought an “improved picture”.

He said: “A request has been made today to the UK government for military assistance in aerial support that can be used to supplement existing resources that are being deployed to tackle the Cairngorms wildfire and we await a response.”

Residents of Nethy Bridge have been taken to a dedicated respite centre at the Macdonald Aviemore hotel. Access roads have been closed amid fears the fire is heading for the village.

Swinney said earlier in the day that changing wind conditions had “intensified the pace of spread of the wildfire, adding that the Scottish fire and rescue service (SFRS) was focusing its resources on creating a firebreak.

“I am extremely grateful to all the first responders who have been working hard to control this fire since it was first reported last Wednesday. I remain in continued contact with SFRS and partners and SGORR [the Scottish government resilience room] will convene again,” he said.

The wildfire, which broke out near the village of Glenmore on 15 July, led to residents and campsites being evacuated. It covered an area of about 6 sq km of heather and small trees at its height and its smoke has drifted as far as Aberdeen, about 60 miles (97km) from where the fire started.

More than 500 firefighters have been mobilised to deal with the blaze alongside specialist wildfire appliances, all-terrain vehicles, helicopter water-bombing operations and partner agencies, senior emergency service officials said.

They added that firefighters “continue to work across a vast and challenging landscape alongside Forestry and Land Scotland, the Cairngorms national park authority, landowners, estate gamekeepers and emergency service partners. Their expertise, local knowledge and support have been instrumental in helping crews respond to this complex and dynamic incident.”

On Saturday morning, a Police Scotland superintendent, Judy Hill, said: “The weather conditions experienced within the Cairngorms over the last 24 hours have added further complexities to this situation. With evidence suggesting the fire is spreading towards Nethy Bridge, the decision has been taken to declare a major incident and evacuate residents as a precaution.”

On Saturday, the SFRA also warned residents in Tomintoul – about 10 miles (16km) to the east of Nethy Bridge – to keep windows and doors closed because of the smoke from the wildfire.