A Swiss husband and his Thai wife were arrested over an alleged meth-fuelled road rampage in Thailand.

Swiss expat Sandro Scharer, 42, and his wife Lamai Scharer, 39, were reportedly high on meth as they quarrelled in a pick-up truck travelling along a highway in Chumphon province, on January 17.

Shocking footage shows a crazed Lamai leaning from the open car door as she allegedly tried to jump out of the moving vehicle while her terrified five-year-old son watched from inside. Motorists driving behind the truck reported the incident to the police.

The couple were nabbed by Highway Police at a road checkpoint along Asia Highway. They were taken to the local police station for questioning.

Footage shows cops escorting Sandro, seen in the video wearing a green shirt, into the building. The Swiss man was seen wiping away tears as he sat and talked to his worried son.

Speaking to the officers, Thai wife Lamai claimed she had been fighting with her husband frequently as he accused her of infidelity.

She said: 'He was paranoid that I was cheating on him. He threw away my phone while we were fighting. I had also been drinking wine earlier. I felt hurt by his actions, so I tried to jump out of the car.'

However, police said they noticed the couple exhibiting 'suspicious' behaviour beyond being drunk on alcohol. Urine tests revealed that the pair had consumed methamphetamine.

Police Lieutenant Colonel Chatchai Nualjing, deputy superintendent of investigation at the local police station, said: 'We had the suspects undergo alcohol tests, then sent them to the Phato Hospital to be tested for drugs. The urine test results showed both of them were found to have methamphetamine, a Category 1 drug, in their systems.'

The couple claimed they had used the banned drugs 'as pain relievers'. Both were remanded in custody at the police station while authorities were evaluating the welfare of their son.

Methamphetamine is considered a 'Category 1' drug under Thailand's Narcotics Act.

Under Thai law, using category 1 substances may be punished with up to three years in jail and a fine of up to 60,000 baht, while possession carries a fine of up to 200,000 baht and up to 10 years imprisonment.

Those convicted of dealing may face life imprisonment and a five million baht fine, depending on the amount involved. Producers, importers, and exporters of Category 1 substances face the same charges and may face the death penalty if it is proven their intent was to sell or distribute on a large scale.