Xi Jingping of China, right, with Rodrigo Duterte at a summit in Beijing last year

The Philippines has relinquished its legal win over the right to territory in the South China Sea, handing a significant victory to China in its claim to sovereignty over the strategically important shipping lane.

Manila and Beijing are negotiating a deal that would enable them jointly to exploit an underwater oil and gas field. In 2016 an international tribunal ruled that the Philippines had exclusive rights over certain areas of the South China Sea, a decision angrily rejected by China.

Since then China has used patrol ships to block the Philippines access to one of these zones, Reed Bank, 85 miles off its coast, preventing it from exploring an alternative to increasingly depleted deposits of energy on which it has so far depended. By compromising