Ayungin Shoal, also known as Second Thomas Reef, is in what Manila calls the "West Philippine Sea," more commonly referred to as the South China Sea.
The South China Sea is the site of a number of overlapping territorial claims and China is asserting national sovereignty over nearly the entire body of water.
Filipino Department of Foreign Affairs spokesman Raul Hernandez said that as Ayungin is 121 miles from Palawan province, it lies well within the Philippines' 200-mile exclusive economic zone, as delineated in the U.N. Nations Convention on the Law of the Sea.
"That's why (China should withdraw its ships from) the area and respect the maritime zones of the Philippines," he told The Philippine Daily Inquirer.
Besides the Philippines, China is also involved in territorial disputes in the South China Sea with Taiwan, Vietnam, Malaysia and Brunei.