"Vietnam is closely monitoring and deeply concerned about the incident on June 17," said Foreign Ministry spokeswoman Pham Thu Hang.
Hang said Vietnam calls for relevant parties to show restraint and act appropriately in accordance with international law, respecting the sovereignty and jurisdiction rights over the exclusive economic zones and continental shelves of coastal nations, which are established in accordance with the United Nations Convention on the Law of the Sea (UNCLOS).
Vietnam has also requested parties to fully conduct the Declaration on the Conduct of Parties in the South China Sea (DOC), respect and abide by international regulations on maritime safety, conflict resolution through peaceful methods, and positively contribute to the maintenance of peace, stability and sustainable development in the region, she said. Vietnam calls the waterway the East Sea.
Filipino authorities on June 18 said certain members of the Chinese coast guard had used speedboats to prevent Filipino vessels from transporting food, water and other supplies for soldiers on the BRP Sierra Madre, which was used by Manila as an outpost at the Second Thomas Shoal a day prior.
The Philippines said the Chinese vessels had displayed "dangerous behavior," causing at least eight Filipino sailors to be injured.
Two rubber boats, dragged around by the Chinese coast guards, have been abandoned in a damaged state.
Meanwhile, Chinese coast guards accused the Philippines of being "entirely responsible for the incident."
They said a Filipino vessel "ignored the constant warnings and dangerously, unprofessionally approached Chinese vessels which were moving normally, leading to an impact."
The Chinese Ministry of Foreign Affairs said the Filipino vessels were trying to transport construction materials and other materials to the BRP Sierra Madre.
Beijing said the actions of the Chinese coast guards were "professional, refrained, appropriate and legal."
The Second Thomas Shoal is a half-floating entity in the South China Sea, and is currently under the control of the Philippines. China also claimed sovereignty over the entity.
The Filipino army used the BRP Sierra Madre to enter the Second Thomas Shoal since 1999, and turned it into an outpost for continued presence. Its stationed troops entirely depend on supplies transported from the land.