Taiwan on Saturday protested to the Philippines over naval ships it sent to disputed South China Sea islands in the latest diplomatic spat between the two governments.

"Taiwan expresses its serious concern and firm opposition over the Philippines' dispatching of naval vessels to the Ren'ai (Second Thomas) Shoal in the Nansha Islands," it said in a statement.

Taiwan's government "denies all unlawful claims to sovereignty over, or occupation of, these areas by other countries," it said.

The statement did not say when or how many Philippine ships were allegedly sent to the area or for how long.

The Philippine government and military spokespeople declined to comment.

The Nansha Islands are at the center of overlapping territorial claims in the South China Sea, including claims by Taiwan, the Chinese Mainland, Vietnam, Malaysia, the Philippines, and Brunei.

The incident comes after the fishing boat Guang Ta Hsin 28 was fired upon by Philippine Coast Guard officers on May 9, in a sea area located 160 nautical miles southeast of Taiwan. The attack resulted in the death of a 65-year-old Taiwanese fisherman.

Philippine deputy presidential spokeswoman Abigail Valte denied on Sunday that Taiwan had set new conditions for the investigation into the death of a Taiwan fisherman by Philippine Coast Guards.

Taiwan has rejected claims that the shooting took place in Philippine waters and that the killing was "unintended." Taiwan's top leader Ma Ying-jeou has described the incident as "cold-blooded murder."

Taiwan's coast guard will escort fishing ships on a regular basis to protect them from harassment by the Philippines, Ma said on May 22.

Amid widespread public outrage on the island, Taiwan's government has rejected repeated apologies from the Philippines and announced a series of economic sanctions against the country, including banning the entry of any more workers.

Taiwan has also recalled its de facto envoy and held a military exercise in waters near the northern Philippines last week.

AFP - Xinhua