An Indonesian court has sentenced a Japanese grandfather to life imprisonment for smuggling methamphetamine into the country.

Masaru Kawada, 73, was arrested in November at Minangkabau Airport in West Sumatra's capital Padang, after customs officials found 2.35 kilograms (5.18 pounds) of crystal methamphetamine in his luggage.

The District Court in Pariaman found Kawada guilty on Wednesday of violating anti-drug law.

Prosecutors had sought a 16-year sentence for Kawada, who argued that he was deceived by someone who asked him to carry a bag and that he did not know he was carrying drugs. His lawyer said they would appeal.

Indonesia has extremely strict drug laws and often executes smugglers. More than 130 people are on death row, mostly for drug crimes. About a third of them are foreigners.