The Association of Southeast Asian Nations has dropped a reference to conflicting territorial claims involving Japan, China and South Korea in a draft of a chairman's statement that was set to be issued later Sunday after a leaders' summit in Phnom Penh.

Diplomatic sources said ASEAN leaders had planned to express concern about Tokyo's disputes with Beijing over the Senkaku Islands in the East China Sea and with Seoul over the Takeshima Islands in the Sea of Japan, but apparently decided against it to avoid "heating up" tensions before a summit that will include the leaders of the three countries Monday, as well as the wider East Asia Summit the following day.

"We expressed our concern on the differences over territorial claims in (the) East China Sea involving China, Japan and (South Korea)," the draft statement, dated Nov. 10, said. "We therefore urged all parties concerned to undertake utmost restraint and to address the issue through peaceful negotiation and dialogue with a view to ensure the maintenance of peace, stability and security in the entire region."