Two of the exercises are being held near the Paracel Islands, one in the East China Sea, and one in further north in the Bohai Sea, the Maritime Safety Administration said in notices on its website.

In the southern part of the Yellow Sea, drills including live-fire exercises will be held from Monday to Wednesday, it said in another notice.

All ships are prohibited from entering the area, it said.

In a bid to train a combat-ready military force, China holds military drills periodically, but rarely do multiple exercises happen at the same time.

Last month, China announced four separate exercises, from the Bohai Sea to the East and Yellow Seas and down to the South China Sea, in what Chinese military experts said was a rare arrangement of drills.

Among those, drills on the Paracel Islands from August 24 to 29 received Vietnam's protests.

Vietnam's Ministry of Foreign Affairs spokeswoman Le Thi Thu Hang said on August 26 that China repeatedly performing drills in the area of the Paracels "violates Vietnam's sovereignty over the islands, goes against the spirit of the Declaration on the Conduct of Parties in the South China Sea (DOC), and is not conducive for negotiations related to the Code of Conduct of Parties in the South China Sea (COC), as well as the maintenance of peace, stability and cooperation across the waters."

Vietnam has repeatedly asserted its sovereignty over the Paracel (Hoang Sa) and the Spratly (Truong Sa) Islands in the East Sea, known internationally as the South China Sea.

All actions regarding the islands without Vietnam's agreement are illegal, Hang has said.