Taipei has rejected condolences from the Philippines over the death of a Taiwanese fisherman following a clash in disputed waters of the South China Sea.

President Ma Ying-jeou threatened to stop processing worker visas for Filipinos unless the Philippine government formally apologizes and agrees on talks over fishing rights in the South China Sea, reports the Financial Times.

This comes after the head of the Philippines’ de facto embassy in Taiwan, Antonio Basilio, visited the family of Hung Shih-cheng and “extended condolences and apologies” on behalf of his nation.

Authorities in Taipei claimed the Philippine coastguard fired on a Taiwanese fishing boat last week, having claimed that it had crossed into Philippine waters. A 65-year-old fisherman was killed.

Prosecutor Liu Chia-kai described the incident as “nothing but a slaughter”, after examining the bullet-ridden vessel.

Philippine president Benigno Aquino called for calm amid mounting tensions over the incident. He also said the Philippine embassy in Taiwan was in talks with Taiwanese foreign ministry officials and had assured them an investigation was being carried out, reports AFP.