900 Chinese firefighters sent back to Sichuan mountain as deadly blaze reignites

Chinese soldiers board on a helicopter in Chengdu in China's southwestern Sichuan province.

A forest fire in southwest China that left 31 people dead reignited on Saturday afternoon, just a day after local authorities said it posed "no further risk", according to the state broadcaster.

Witnesses spotted at least three helicopters flying over the site in Muli county, Sichuan province, on Sunday morning, China Central Television reported.

The fire returned to the remote spot at an altitude of more than 3,700 meters (12,000 feet) in the northeast of the forest at about 5pm on Saturday, and because of the windy conditions soon spread to an area of five to 10 hectares (12.5 to 25 acres), the report said, citing sources from Muli and the Liangshan Yi autonomous prefecture.

Almost 900 firefighters from nearby towns and regions were dispatched to tackle the blaze, the first of whom arrived on the scene about 5am on Sunday.

The press office of the local fire brigade issued a statement saying the fire reignited in an area under a rocky overhang that was mostly hidden from view.

"Burning embers then rolled down the hillside and set fire to more trees," it said.

As the flames rose up into the canopy they became a crown fire - a type of blaze that spreads from treetop to treetop - and sparks were blown to the eastern side of the forest which had escaped last week's devastation, the statement said.

The initial fire broke out about 6pm on March 30 and was thought to have been brought under control on Tuesday.

On Friday, officials from the Liangshan branch of the Sichuan Forest Fire Brigade said there was no risk of it reigniting and that all firefighters had been withdrawn from the scene.

"The last three fire points have completely settled," they said in a statement. "The whole site is fully under control and there is no risk of it restarting."

An investigation into the fire, which left 27 firefighters and four helpers dead, concluded it had been caused by lightning. Acting on witness accounts, investigators identified an 18-metre pine tree split by lightning as the origin point.

Most of the victims were killed by a huge fireball that was created by the explosive combination of wind, dry air and combustible materials, state media reported earlier.

A firefighter who survived the experience said the fireball moved so quickly that trees on the ridge were consumed within seconds, with flames rocketing up as if "someone triggered a huge flame-thrower".

The local government said efforts to tackle the blaze had been badly hampered by the high altitude, difficult terrain, poor vehicular access, thick humus layer and difficulty getting water to the site.

This article was first published in South China Morning Post