(Bloomberg) -- Indonesia’s military has stepped up naval and aerial patrols of the Natuna Sea area because of a rising number of Chinese fishing vessels in the region.

The Southeast Asian nation has deployed three ships and two aircraft in the gas-rich North Natuna Sea, and two additional vessels are on the way to join the group, Yudo Margono, commander of the Joint Regional Defense Command, said in statement.

The deployment came after Indonesian Foreign Affairs Minister Retno Marsudi said China should comply with the United Nations Convention on the Law of the Sea and reiterated Jakarta’s position that it will never acknowledge Beijing’s nine-dash line, a demarcation it uses to show its claims in the area.

Marsudi sent a diplomatic note to Beijing protesting the intrusion of Chinese vessels into Indonesia’s special economic zone in the area, according to a statement on the Cabinet Secretary’s website.

China is in dispute with several Southeast Asian countries over its claim to areas of the South China Sea. On Dec. 12, Malaysia submitted to the United Nation’s Commission on the Limits of the Continental Shelf information on what it believes are its its sovereignty rights in the area.

--With assistance from Arys Aditya and Tassia Sipahutar.

To contact the reporter on this story: Harry Suhartono in Jakarta at hsuhartono@bloomberg.net

To contact the editors responsible for this story: Thomas Kutty Abraham at tabraham4@bloomberg.net, Stanley James

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