Fire rages through a popular national park in northern Thailand this morning (February 17) after a discarded cigarette is believed to have started the inferno.

Crews have spent around 24 hours battling the flames at the Phu Kradueng National Park in Loei province.

Residents said a blaze began at the Mesa Cliff viewpoint on Sunday (Feb 16). Investigators believe it may have started from a discarded cigarette.

Park chief Sombat Pimprasit said the fire was brought under control at around 9am this morning. He said 92 officers and 130 volunteers battled the flames.

However, the smoke was still rising from the scorched woodland, where 1,344 acres of land was burned.

Sombat said: ''The park was busy at the weekend with many people. The fire could have been caused by human activity but we still do not know.

"This was a big fire that has not happened here for some time now, which made me think someone had carelessly left a burning cigarette butt.

"I have assigned the officers to be on guard watching the park and preparing the equipment in case the fire breaks out again."

Investigators are now probing what caused the fire amid suspicions that a visitor's carelessly discarded cigarette may have ignited dried grassland before the flames quickly spread.

The Phu Kradueng National Park is the second oldest national park in Thailand, after Khao Yai.

It is known as a place where couples can prove their “true love” by successfully hiking together. Many domestic tourists visited the area at the weekend to mark Valentine’s Day on Friday (Feb 14).