The Philippines has lodged a diplomatic protest against China over the presence of a floating structure in the disputed Scarborough Shoal in the South China Sea. The country's foreign ministry took what it described as appropriate diplomatic action after authorities confirmed the existence of the structure in the contested area.

According to the Philippines' South China Sea task force, the floating structure measures approximately six metres by six metres and appears to have an antenna installed on it. Officials said the structure was first seen at the entrance of the shoal and was later observed inside the lagoon. The task force added that the installation appeared to be manned, citing the latest images provided by the armed forces.

The statement did not specify when the photographs were taken. However, Philippine Defence Secretary Gilberto Teodoro had earlier revealed that he had received preliminary information regarding the structure. Speaking on the sidelines of the Shangri-La Dialogue in Singapore on May 30, Teodoro said he had been informed about the presence of the installation at the shoal.

The South China Sea task force stated that authorities are closely monitoring the situation. Officials are also assessing the structure's nature, purpose and possible implications. The task force maintained that Scarborough Shoal falls within Philippine territory and maritime zones under international law.

In its statement, the task force said, “The Philippine government will continue to take appropriate actions consistent with international law and in defence of the country’s national interests.” It further stressed that the protection of the country's sovereignty and jurisdiction “remains a paramount consideration”.

China responded to the Philippines’ protest by reiterating its claim over the disputed area. On June 9, China's foreign ministry stated that Beijing has “indisputable sovereignty” over Scarborough Shoal, which China refers to as Huangyan Island, as well as the surrounding waters.

Chinese officials defended activities taking place in the area. They said operations, including scientific research, are lawful and fall within China's rights. Foreign ministry spokesperson Lin Jian urged the Philippines to stop what Beijing views as provocative actions.

During a regular press briefing, Lin said, “China urges the Philippines to stop its maritime infringements, provocations and inflammatory hype.”

The latest development comes amid long-standing tensions between the two countries over competing claims in the South China Sea. Scarborough Shoal remains one of the most sensitive flashpoints in the maritime dispute.

Satellite images obtained by Reuters on June 5 confirmed the presence of a structure near the entrance of the lagoon. However, images captured later showed that the installation was no longer in the same location. It remains unclear whether the structure was moved or removed.

Scarborough Shoal is located around 200 kilometres from the western coast of the Philippines. The area is known as a rich fishing ground and is important for local fishermen. In comparison, the shoal lies about 874 kilometres from Hainan Island, which is the nearest Chinese landmass.

China has maintained a continuous presence in the area for more than a decade. Since 2012, Chinese coastguard vessels and maritime militia ships have regularly operated around the shoal. Their presence has been a recurring source of friction between Beijing and Manila.

The issue of sovereignty over Scarborough Shoal remains unresolved. No final international agreement has determined ownership of the atoll. However, a landmark ruling by an arbitral tribunal in 2016 largely supported the Philippines' position in its case against China.

The tribunal concluded that China's blockade of the shoal violated international law. It also ruled that the area had traditionally been used as a fishing ground by several countries. The decision was viewed as a significant legal victory for the Philippines, although China rejected the ruling and continues to assert its claims over the area.

The discovery of the floating structure has once again highlighted the ongoing dispute in the South China Sea. While both countries continue to defend their positions, Philippine authorities say they will keep monitoring developments and take actions they believe are necessary to protect the country's interests and territorial claims.