Since September, residents on South Korea's Jeju island have been spotting small packs of what appear to be bags of Chinese tea washed ashore. Upon closer inspection, however, they were found to contain ketamine.

Some 28kg (62 lbs) of the drug, wrapped in foil and labelled with the Chinese character for tea, have been found on at least eight occasions, police say.

Ketamine is used as an anaesthetic in medical procedures, but its recreational use is illegal in South Korea. It can cause severe physical and mental damage, including to the heart and lungs, when misused.

The Jeju Coast Guard has formed a team to trace possible sea and land routes through which the drugs may have entered the country.

Authorities have also warned residents not to touch or open any suspicious objects found along the shore, asking them to instead report such discoveries to police.

On 15 October, a beach cleaner found 20kg of these tea bag drugs - the largest haul in the last two months - along the coast of Seogwipo in southern Jeju.

Earlier this week, a team of more than 800 soldiers, police officers and civilian volunteers was deployed to comb the beaches in Jeju City, along the holiday island's northern coast. Investigators are now focusing on the possibility that the drugs drifted to Jeju via ocean currents.

Jeju residents have shown concern over the presence of illicit drugs on their coastlines. One resident expressed fear seeing so many people searching for the drugs, worrying about the potential for children to come in contact with the dangerous items.

Experts suggest that sophisticated smuggling methods could be behind these drug packages, raising alarms about the safety and security on the island.