A Sri Lankan court sentenced five Indians and three locals to death on Thursday after finding them guilty of smuggling drugs onto the island while claiming to be fishermen.

Colombo High Court judge Preethi Surasena convicted all eight men who were arrested in November 2011 off the island’s northern coast carrying heroin, a court official said.

Drug convictions carry a mandatory death sentence which is almost always commuted to life in prison. Sri Lanka has not carried out an execution since 1976.

“They claimed they were genuine fishermen, but the court upheld evidence that they transported nearly a kilo (2.2 pounds) of heroin from India to Sri Lanka,” the unnamed official said.

The official said the men claimed they were in Indian waters at the time of their arrest, but recordings from their onboard navigational equipment showed they were in fact in Sri Lankan waters.

The five Indians from the southern Indian state of Tamil Nadu were expected to appeal to Sri Lanka’s Supreme Court.

“Now that the lower court has given its judgement, we intend through our High Commission to appeal to a higher court,” Indian foreign ministry spokesman Syed Akbaruddin told the NDTV network in New Delhi.

Fishermen from the two countries straying into each others’ waters is a thorny issue for Colombo and Delhi.

Tamil Nadu has repeatedly accused Sri Lanka’s navy of harassing their fishermen and urged Delhi to take firm action against Colombo.

Sri Lanka denies the charges, and says Indian fishermen are regularly straying into Sri Lankan waters and depriving local fishermen of their livelihood.

The two countries are separated by a narrow strip of sea known as the Palk Strait which is also a rich fishing ground.

During the height of Sri Lanka’s separatist war in the island’s northeast, close to southern India, fishing provided a cover for lucrative smuggling of arms and fuel to the rebels.

Sri Lankan authorities say smugglers are now bringing narcotics into the island for shipping to other destinations.