KANO, Nigeria: Three doctors killed in a knife attack in a volatile town in northeastern Nigeria on Sunday were South Korean and not Chinese as originally reported, police said.

Men armed with knives slit the throats of the three Korean doctors in a pre-dawn attack in the town of Potiskum, police said, in the latest such killings in recent months.

"Further investigations have shown that the victims were Korean nationals and not Chinese as earlier stated. They were doctors from South Korea," Yobe State police commissioner Sanusi Rufa'i told AFP.

A senior military officer in the state also said they were from South Korea.

In Seoul, the foreign ministry said it was checking the reports, but noted that few Koreans live in the town.

"The chance that the slain would be Koreans is not high," a foreign ministry official told Yonhap news agency. "But we are checking further related situations via diverse channels."