Japan will give thousands of helicopter parts to the Philippines to keep its military choppers airborne, helping Tokyo gain clout with Manila in a contest with China to secure influence over the strategic South China Sea nation, four sources said.

Military diplomacy is a new means for Japan to confound China's bid for control in the bitterly contested South China Sea as Prime Minister Shinzo Abe seeks a regional military role amid a retreat from decades of state pacifism.

The pact could be the first in a series of similar deals as Tokyo cranks up defense diplomacy with Southeast Asian nations eager for hand-me-down patrol aircraft, ships and other military equipment.