A jealous Thai man allegedly set his girlfriend on fire 'because she waved at a neighbour'.

Samroeng Muangsuk, 50, was seen on CCTV arguing with Suratana Buachum, 47, outside her home in Bangkok, Thailand on April 10.

He was reportedly angry because Suratana had waved at a neighbour while saying 'hello' several minutes before.

Samroeng allegedly poured a five-litre can of gasoline on the neighbour's motorcycle but saved some to attack his girlfriend.

He is said to have ignited the two-wheeler in the parking lot then walked up to his girlfriend’s apartment to douse her in flames before fleeing.

Suratana was heard screaming in pain while calling for help until neighbours saw her and extinguished the fire. She was rushed to the Mongkutwattana Hospital with third-degree burns.

Police Colonel Lieutenant Somjai Rodyang said Suratana is in a critical condition.

He said: ‘We tracked down the man by following his route in the street CCTV. He will be questioned and charged accordingly.’

Before the incident, the couple reportedly had a fight when the woman said ‘hi’ and asked for help from a neighbor, who owned the motorcycle which Samroeng burned.

The boyfriend allegedly hit the woman in the face during the fight until he returned with the gasoline.

Rescuers found a burned floral-patterned shirt and bra on the burn site, while Suratana was wearing only black shorts with burns covering her face and body.

Samroeng was remanded in custody after being arrested by officers on suspicion of criminal damage and attempted murder. Investigations on the incident are ongoing.

Police Colonel Lieutenant Somjai Rodyang added: 'The situation is aggravated because there is an emotional disagreement between the two lovers. We are hoping to interview the girlfriend when she recovers.'