Three Mexican brothers and two other people have lost their final appeals against death sentences for drug trafficking in Malaysia.

The Mexicans are from Sinaloa state, the cradle of their country's drug trade, but have no criminal record at home. They were arrested at a secluded drug-making factory in Malaysia in 2008, and claimed they had been cleaning the place, not making drugs.

Their lawyer Kitson Foong says a five-man bench in the Federal Court, Malaysia's highest court, unanimously rejected their appeal Thursday. The defense has argued that the evidence was tampered with.

Foong says his clients may seek a judicial review of the court's decision.

The other defendants are a Singaporean and a Malaysian.