Another ASEAN summit will be held in November and will include other multilateral meetings such as the East Asia Summit, which the leaders of China, Japan, the USA and other dialogue partners are expected to attend.
ASEAN members Vietnam, Malaysia and Brunei also claim parts of the sea, but China insists it has sovereign rights over almost all of it.
In the chairman statement issued at the end of the Asean Summit here yesterday, a proposed reference to full respect for legal and diplomatic processes has been taken out from the South China Sea section, a move seen by some senior Asean officials as silencing an global arbitral court backing Manila's claims in the area.
Duterte and some Philippine defense officials were given a tour by Chinese naval and diplomatic officials inside the Chinese guided destroyer Chan Chung (DDG-150).
"The relevant situation at this ASEAN summit again fully shows the positive changes in the South China Sea situation and that the joint wish of countries in this region is to seek stability, promote cooperation and seek development, and this should be respected and supported by all sides".
The Chinese ships arrived in the Philippines on Sunday for a three-day goodwill visit, the first Chinese naval fleet to make a port call to the Southeast Asian country in seven years, a sign of warming ties between the two countries.
That Philippines government in 2013 challenged Beijing by lodging a case with the Permanent Court of Arbitration in 2013.
Duterte said if the current tensions lead to nuclear war, "no one will win", the source said.
North Korea quiet amid expectation of missile follow-up
North Korea staged a massive live-firing drill on Tuesday (25 April) with its leader Kim Jong-un presumably overseeing the event. North Korean soldiers walk in front of bronze statues of North Korea's late founder Kim Il-sung and late leader Kim Jong Il.
Southeast Asian leaders concluded a summit here on Saturday by dropping references to the China's massive island-building in the South China Sea and to a landmark court ruling that rendered such expansion illegal in response to Beijing's lobbying.
An earlier draft of the chairman's statement seen by AFP cited a reference to "respect for legal and diplomatic processes".
However, leaders of the region agreed a framework of the code of conduct in the disputed South China Sea must be completed by the middle of the year to avoid further tensions within the area, the envoy noted.
Meanwhile, Patron said efforts ASEAN and China continued to craft the framework of a binding code of conduct among claimant parties in the South China Sea.
In addition, he said the issue of terrorism had also drawn attention at the summit in which Malaysia said the country's contribution, including the radicalization programme, had achieved a high level of success.
"Dialogue relations can be made more productive, constructive if the valued principle of non-interference in the internal affairs of the ASEAN member-states is observed", Duterte said.
Duterte, elected past year, has changed foreign policy by playing down his country's territorial dispute with China over large parts of the South China Sea in favor of greater economic aid and investment.
But ASEAN can not antagonize China too much.
The draft shows that other matters tackled included East Timor's application to become an ASEAN member.