China criticized the Philippines for failing to keep its commitment to tow away a warship that was "illegally stranded" in China's Ren'ai Reef in 1999 and attempting to repair and reinforce it for permanent occupation of the reef, a spokesperson said on Monday.

The Philippine coast guard and armed forces claimed on Saturday that Chinese coast guard vessels intercepted and fired water cannons at Philippine vessels transporting replacement personnel and supplies to the warship, saying Chinese actions violated international law.

A spokesperson for the China Coast Guard rebutted the claims, and stressed the reef has always been part of China's Nansha Islands.

In 1999, a Philippine warship illegally ran aground on the reef, and China immediately lodged its disapproval, the spokesperson said in a statement, noting the Philippine side "has repeatedly" promised to remove the stranded warship.

"However, after 24 years, the Philippines not only failed to remove the warship but also attempted to extensively repair and reinforce it, in order to permanently occupy Ren'ai Reef", said the statement.

It asserted the Philippine actions infringe upon China's sovereignty, violate its own commitments and go against international law and the Declaration on the Conduct of Parties in the South China Sea signed between China and ASEAN countries.

China urges the Philippines to remove the stranded warship  and restore the original state of the reef, the spokesperson said, adding China has made temporary special arrangements for the transportation of necessary supplies such as food to the warship.

However, in recent times, under the guise of personnel rotation and supply transportation, the Philippines has continuously loaded large quantities of construction materials onto the warship.

"China has repeatedly expressed serious concerns  through diplomatic channels and proposed negotiations on managing the situation in Ren'ai Reef, but the Philippines has refused to respond," the spokesperson said.

Recently, after learning that the Philippines would send more materials, China has made its issues known at multiple levels and through various channels, demanding the latter not send ships into the reef without authorization and not transport building materials for large-scale maintenance.

Chinese vessels lawfully intercepted the two Philippine ships and conducted warning measures, it said, noting the Chinese side used water cannons to avoid a collision after multiple verbal warnings proved ineffective.

"The operation was conducted professionally and was beyond reproach," the spokesperson said. 

China's position is clear, the statement said, adding China will continue to take measures to firmly defend its territorial sovereignty. 

"At the same time, China once again urges the Philippines to accept China's proposal, engage in negotiations and explore specific measures to manage the situation in the reef," said the spokesperson.