The Philippine military said Saturday it has replaced a key commander overseeing forces in the South China Sea, including Filipino troops garrisoned on a disputed reef.

Rear Admiral Alfonso Torres Jr will replace Vice Admiral Alberto Carlos as chief of the Western Command on Palawan island, which is the closest Philippine landmass to the hotly contested Spratly Islands.

The military said in a statement the move was part of "ongoing changes in leadership and key positions within the military which is necessary for the institution to adapt to evolving security environment and effectively address emerging challenges."

It follows a series of incidents involving Philippine and Chinese vessels near disputed reefs in the South China Sea that have strained diplomatic ties.

These have included water cannon attacks by China Coast Guard vessels as well as minor collisions in recent months that Manila says damaged Philippine boats and injured several soldiers.

Beijing claims most of the South China Sea, including the Spratly Islands, despite an international tribunal ruling that its assertion has no legal basis. 

The Philippines, Vietnam, Malaysia and Brunei have overlapping claims to parts of the sea.

The announcement of Carlos' replacement follows a diplomatic row between Manila and Beijing over an alleged agreement struck by Chinese officials with the Western Command.

The Chinese embassy in Manila claims the deal related to conduct of Chinese and Philippine vessels around Second Thomas Shoal, which Beijing calls Ren'ai Jiao, where Filipino troops are stationed on a grounded naval vessel.

It alleged Manila reneged on the agreement, whose terms it has not made public, causing Chinese law enforcement to take "necessary measures" to protect their territory.

Philippine Defense Secretary Gilberto Teodoro and National Security Adviser Eduardo Año have denied there was such an arrangement.

Año later called for the expulsion of certain unnamed Chinese embassy officials he accused of violating Philippine laws, including allegedly wiretapping an unnamed Philippine military official.

Local media have quoted an unnamed Chinese embassy official as saying the deal called for limiting the number of Philippine supply vessels and escort boats to Second Thomas Shoal as well as Chinese vessels around the reef.