MANILA -- A joint investigation by Manila and Beijing into the sinking of a Filipino boat by a suspected Chinese militia vessel "is not the proper forum to discuss" poaching in the South China Sea, the Department of Justice said Tuesday.

The Filipino boat was anchored near Recto Bank (Reed bank) -- which is part of Manila's Exclusive Economic Zone -- when it was hit by the Chinese craft last June 10, causing it to sink and leaving 22 fishermen adrift for hours before they were rescued by a Vietnamese vessel.

"The poaching angle, I agree, is a collateral issue to the collision incident. But the marine inquiry is not the proper forum to discuss this much broader economic issue," DOJ Secretary Menardo Guevarra said in a statement.

Other countries and coastal states with their own EEZs are involved in the issue, he said.

Beijing said its trawler merely "bumped" into the Philippine boat and tried to rescue the fishermen but was "afraid of being besieged by other Filipino fishing boats."

China is claiming nearly all of the South China Sea, conflicting with partial claims of the Philippines, Vietnam, Malaysia, Brunei, and Taiwan.

Competing claims over the South China Sea are a point of regional contention because trillions of dollars of goods pass through it, and rich petroleum reserves are thought to sit deep beneath its waters.

Reed Bank, an area claimed by Manila and Beijing, is within the Philippines' 200-nautical-mile EEZ and far from China's nearest major landmass.

With a report from Agence France Presse and Mike Navallo, ABS-CBN News