Philippines Defence Minister Delfin Lorenzana has said China's arms buildup on the disputed islands in the South China Sea is "very troubling".
Lorenzana's comments come a day after Foreign Minister Perfecto Yasay confirmed that Manila had lodged a low-key diplomatic protest with Beijing in December, after a US think thank reported that China appeared to have installed anti-aircraft and anti-missile weapons on its man-made Spratly islands in the strategically vital South China Sea.
"The actions of China in militarising those disputed features are very troubling. They do not square with the Chinese government's rhetoric that its purpose is peaceful and friendly," Reuters cited Lorenzana as saying.
Lorenzana's comments appear to be much stronger than those made by Yasay. The latter refrained from criticising Beijing saying Manila would handle the issue carefully and let the public know that the country was not "sleeping on the job".
"When something happens that can pose us some kind of threats to our sovereignty rights we issue a note verbale so we can talk about it and make sure it is properly addressed," he told ABS-CBN television.
A report by the Centre for Strategic and International Studies said the anti-aircraft guns and close-in weapons systems were placed on all seven of the islands that China has created in the international waterway. The weapons are thought to be designed to guard against any missile attack.
China, however, defended its militarisation. Its foreign ministry spokeswoman Hua Chunying said the country had the right to deploy on the man-made islands "necessary and appropriate defence equipment to protect its sovereign territory".
Speaking at a daily news briefing, she repeated calls to hold two-way talks between China and countries with overlapping claims. She said work between the warring parties was "progressively lowering the temperature in the South China Sea".
Lorenzana opined that a diplomatic protest was the correct step taken by the Philippines. Although Filipino President Rodrigo Duterte has been leaning towards China seeking warm relations despite the territorial row, the government in Manila had a duty to protect the national interest, the defence minister added.