JAKARTA 

Indonesia will send two more ships to strengthen its defense in the disputed Natuna waters following trespassing by Chinese coastguard vessels a few days ago, said the country's Maritime Security Agency on Thursday. 

First Admiral Nursyawal Embun, the agency's director of sea operations, told Anadolu Agency that the reinforcement was sent to deal with any incursion by a Chinese vessel.

"This is the first time we face [such behavior], they [China] insist that the five degrees latitude of Indonesia’s exclusive economic zone (EEZ) is their territory," he said.

Embun said there were currently two or three Chinese coastguard vessels in the Indonesian EEZ.

On Monday, the country filed a protest note against China over violations of its territory by a Chinese coastguard vessel in the Natuna waters in South China Sea.

Natuna waters are believed to hold significant reserves of undiscovered oil and gas and serve as a crucial passage for commercial shipping.

China claims nearly all of the 3.5-million-square-kilometer (1.35-million-square-mile) South China Sea, overlapping with the maritime claims from Vietnam, Taiwan, the Philippines, Malaysia, and Brunei.