Updated

Malaysia's appeals court Wednesday upheld the convictions and death sentences on three Mexican brothers for drug trafficking, forcing them to appeal to the nation's top court as a last resort.

The brothers surnamed Gonzalez Villarreal -- Luis Alfonso, 44, Simon, 37 and Jose Regino, 33 -- were sentenced to hang by the Kuala Lumpur High Court last year for their part in a methamphetamine operation along with a Malaysian and a Singaporean.

The suspects were arrested at a factory in southern Malaysia in 2008, with police seizing almost 30 kilograms (66 pounds) of methamphetamine and chemicals used to produce the drug.

At the Court of Appeal, the brothers' lawyer argued that the alleged drugs used as evidence in their conviction had altered due to the passage of time before they were subjected to analysis by a chemist.

But the appeal was dismissed, leaving them with no other option but to take the matter to the Federal Court.

"I raised nine other points. The appeal will be filed ASAP," the trio's lawyer, Kitson Foong, told AFP.

The three brothers, from the northern state of Sinaloa, are believed to be the first Mexicans sentenced to death for drug trafficking in Malaysia.

The accused have claimed they were merely workers taken to the premises to clean them and were unaware of any illegal activity.

Hundreds of Malaysians and foreigners -- including many from Iran -- are on death row in Malaysia, mostly for drug trafficking.

The offence carries a mandatory death penalty in Muslim-majority Malaysia, though executions are not publicly announced and activists say few are thought to have been hanged in recent years.