NUSA DUA - China's aggressive actions in the South China Sea appear to be motivated by a hunger to exploit the area's rich oil and gas resources, the Philippines' foreign secretary said Saturday.

Speaking on the sidelines of an Asian security forum in Indonesia, Albert del Rosario also said China's behavior in the disputed waters raised concerns about how it would treat its neighbors as it became more powerful.

"I think the wealth of the area in terms of hydrocarbon assets could stimulate an increased interest in the area," del Rosario told AFP when asked why China had, according to the Philippines, become more aggressive.

He said the Philippines was looking at the South China Sea events through a broader window of how China intended to treat other countries as it became more powerful.

"I think there is that concern that China is becoming more powerful," he said.

"We support their progress and their growth. It is good for the region. But at the same time it is our expectation that their strength and their growth and their influence will be exercised in a responsible way."

China claims all of the South China Sea, even up to the coast of Southeast Asian countries, as part of its historical territory.

The Philippines, Vietnam, Malaysia, Brunei and Taiwan also have overlapping claims to all or parts of the sea, which is believed to be extremely rich in oil and gas deposits.

In recent months, the Philippines and Vietnam have accused China of increasingly aggressive behavior in the sea, such as harassing fishermen and oil exploration vessels.

The Philippines has said Chinese forces shot at Filipino fishermen, deployed navy patrol boats to intimidate an oil exploration vessel and placed markers on some of the islets.

Del Rosario said these intrusions occurred within 85 nautical miles of the nearest Philippine island of Palawan, but nearly 600 nautical miles from the nearest coast of China.

He insisted China's claim to all of the sea, based on a Chinese map with nine dashes outlining its territory, would be rejected in an international court.

"We take the position that China's nine-dash claim to sovereignty over the South China Sea is baseless," he said.