President Benigno Aquino III and President Truong Tan Sang, who arrived for a three-day state visit, also were to discuss proposals to involve other countries, and possibly the United Nations, in seeking a solution to the disputes over the islands, which they claim along with four other countries and territories, including China.

Aquino said he and Sang agreed that the disputes should be resolved based on international law, particularly the 1982 U.N. Convention on the Law of the Sea, and through multilateral dialogue and consultations.

They stressed the importance of fully enforcing a 2002 nonbinding accord between China and the 10-member Association of Southeast Asian Nations, which calls on claimants to settle their disputes peacefully and avoid hostile acts, Aquino said.

Vietnam and the Philippines, along with Spratlys claimants Malaysia and Brunei, belong to ASEAN.

Vietnam backed calls for turning the 2002 accord into a stronger, legally binding agreement, Sang said.

“We again confirm the importance of the maintenance of peace, stability, security, safety and freedom of navigation in the East Sea,” Sang said, using the Vietnamese name for the South China Sea.

China wants bilateral negotiations with other claimant countries to resolve the disputes over the potentially resource-rich Spratlys and has rejected any role by non-claimant countries like the United States.

Aquino was to propose that the Philippines and Vietnam work together to raise the territorial conflicts in international forums, including at an ASEAN summit next month in Indonesia, according to Philippine documents. That event will also be attended by the United States, Russia, Japan, South Korea, Australia and New Zealand.

Both sides signed an accord to increase information-sharing between their navies to allow them to better respond to natural calamities and carry out “maritime security operations,” according to the Philippine documents.

Another agreement would set up a hotline between the countries’ coast guards and marine police to strengthen their capability to monitor “maritime incidents,” protect their marine resources, prevent smuggling, drug trafficking, illegal immigration and piracy, the documents said.

The accords would help the countries monitor the South China Sea, including possible foreign incursions into each other’s territorial waters, Philippine Foreign Secretary Albert del Rosario said.

“We want to know what’s going on in those seas and we want to be able to exchange information and share intelligence,” del Rosario told reporters.

The Philippines and Vietnam have accused Chinese vessels of repeatedly intruding this year into Spratlys areas that they claim and of disrupting oil explorations well within their territorial waters. China has denied the accusations and reiterated its claim to the entire South China Sea.