Notice to shipping comes amid rising tension between Beijing and Manila over disputed Scarborough Shoal.

The Guangdong Maritime Safety Administration said the warning would be in place from 6am (22:00 GMT to 11:30am (03:30 GMT) and from 6pm (10:00 GMT) to 9:30pm (13:30 GMT) on September 28.

“Military exercises will be conducted in some waters of the South China Sea and navigation is prohibited,” state broadcaster CCTV reported. It did not elaborate on the location of the exercises.

China claims almost the entire South China Sea under its controversial nine-dash line.

In recent months, tensions have risen with the Philippines, whose claims overlap with China’s, over the Second Thomas Shoal and Scarborough Shoal.

Both are within Manila’s Exclusive Economic Zone (EEZ), defined under the United Nations Convention on Law of the Sea (UNCLOS) as generally extending 200 nautical miles (about 370km) from shore, within which the coastal state has the exclusive right to explore and exploit.

Earlier this week, the Philippines coastguard cut a 300 metre floating barrier installed by China that it said was blocking fishing boats’ access to Scarborough Shoal, which Beijing seized from Manila after a months-long standoff in 2012.

Late on Wednesday, the Chinese coastguard disputed that version of the events, saying the barrier had been deployed on Friday when a Philippine vessel entered the area “illegally” and was removed the following day.

“I would also like to reiterate once again. Huangyan Island is China’s inherent territory,” Wang Wenbin, a spokesperson at the Chinese Foreign Ministry, claimed at a regular press briefing, referring to Scarborough Shoal by its Chinese name. Manila refers to it as Bajo de Masinloc.

The rocky outcrop is a prime fishing spot and has been a site of contention for years.

Both countries claim sovereignty over the shoal, which lies about 120 nautical miles (about 222km) from the Philippine island of Luzon, and 594 nautical miles (about 1,100km) from China’s southern island of Hainan. China has maintained a coast guard presence there ever since the 2012 standoff.

Brunei, Malaysia and Vietnam also claim parts of the sea near their coast and have reported incidents of harassment by Chinese ships.

In a separate report early on Thursday, China’s state media also reported several bombers from the Southern Theater Air Force, which covers the South China Sea, held night-time exercises on Wednesday.

The report did not elaborate on exactly where the exercises took place.