Photo taken on Jan. 28, 2020 shows the sky turned red by the Orroral fire at the Namadgi National Park in Canberra. (Xinhua/Chu Chen)

A bushfire south of Canberra is recognized as the most serious bushfire threat since 2003 and has engulfed more than 10,000 hectares in the remote Orroral Valley.

CANBERRA, Jan. 29 (Xinhua) -- A bushfire in the south of Canberra is recognized as the most serious bushfire threat to the Australian capital since 2003, according to local sources on Tuesday.

The fire, believed to be started on Monday by the landing of a defence helicopter, has engulfed nearly 8,000 hectares as of 7:30 p.m. local time, said a report by the Australian Broadcasting Corporation.

"This is the most serious situation we have faced since the 2003 bushfires," said Andrew Barr, Chief Minister of the Australian Capital Territory (ACT).

Fires entered the suburbs of Canberra in 2003, killing four people, injuring 430 and destroying hundreds of homes.

The Department of Defence said that the fire was possibly caused by a helicopter, the landing lights of which set the grass on fire with heat.

Residents in south Canberra near the fire zone are urged to closely monitor the situation and activate their survival plans.

The ACT Emergency Services Agency believed that the upcoming heatwave would make it difficult to control the fire.■