Three unidentified South Korean nationals were found dead with gunshot wounds to their head in the Phillipines Noel Celis/AFP

The bodies of three South Koreans with gunshot wounds to their head were found in the Philippines, signalling they could be the latest victims in a string of killings in the country. South Korea's foreign ministry confirmed the deceased as its nationals on Thursday (13 October).

The Filipino police recovered the bodies of two men and a woman, all over the age of 40, from a sugar cane field on Tuesday (11 October).

The officials said they received a tip-off from a local farm worker who first spotted the bodies in Bacolor town in northern Pampanga province outside the capital Manila, according to media reports.

One of the men was found with his feet bound by packaging tape. Police official Victor Eduardo, who investigated the killings, said the other man and the woman could have been strangulated as they had visible marks around their neck, while the woman's left wrist was tied with a tape, the Associated Press reported.

South Korean officials are working with Filipino authorities to investigate the case. They have not yet identified the motive or the suspects who carried out the killings, according to Reuters. The local police in Bacolor said they were seeking the help of the local Korean community in the province to identify the victims.

This is the fourth homicide case involving South Koreans in the Philippines this year, taking the tally to six. Since 2013, more than 10 South Korean nationals were reported to have been killed each year.

While it is not clear why the South Koreans were killed, the country they were found dead in is reported to raise questions. However, Sonia Alvarez, Chief of police at Bacolor, ruled out that the deaths were related to drugs and said it could instead be a "crime of passion or indebtedness".

"Not all (the deaths) are related to the war on drugs," Philippine National Police spokesman Dionardo Carlos told Reuters. He confirmed that of the current given numbers only 1,566 drug suspects were killed in police operations, while the remaining 722 deaths were still under investigation or had been already investigated.