HONG KONG • Mother Nature lent a hand to Chinese firefighters who had been battling a massive forest fire for days in a mountainous region near the Russian border.

It started to rain on Friday afternoon and a sudden heavy snowfall overnight covered the Bilahe Beidahe Forest in Inner Mongolia with an 18cm blanket of snow.

Although the snowfall helped douse the flames, the abrupt change in weather presented the firefighting crew with a new problem: They were neither equipped nor dressed to deal with the sub-zero blizzard conditions.

The blaze had broken out in dry, warmer-than-usual conditions early last week, so the crew was wearing relatively light clothing when they arrived at the fire site.

But temperatures plunged to minus 5 deg C overnight by the weekend.

"The firefighters are extremely exhausted and their clothing is too thin," Mr Yan Hongguang, head of the local forest protection bureau, told Xinhua.

"The heavy snow also makes it difficult to transport supplies and to reach anyone who might be injured."

More tents and other supplies had been sent to the area, reported South China Morning Post.

The blaze, caused by smouldering embers dumped by a local worker, spread to 11,500ha amid the dry weather and strong winds.

It was the second large forest fire to hit the Daxinganling prefecture in Inner Mongolia in a week amid high temperatures and dry conditions. More than 9,000 firefighters, including more than 3,000 forest police, were dispatched to help put out the fire.

State media reported that 40 million yuan (S$8 million) in emergency funds have been earmarked to fight forest fires in the country's remote north-east.