Defense Secretary Chuck Hagel will depart Thursday on a tour of Southeast Asia to bolster US military ties with regional partners who face increasing concerns over maritime disputes with China.

Hagel announced on Tuesday he will fly to Malaysia, Indonesia, Brunei and the Phillippines in a week-long visit, with a meeting of ASEAN defense ministers on August 28-29 serving as an anchor for the trip.

Rival territorial claims in the South China Sea are expected to feature high on the agenda of the ASEAN discussions in Brunei next Wednesday and Thursday, officials said.

Countries in the 10-member Association of Southeast Asian Nations have vowed to present a united stance to convince China to approve a binding code of conduct for handling disagreements in the strategic South China Sea.

In Brunei, Hagel also plans to hold talks with China's defense minister, General Chang Wanquan, who will be attending the ASEAN session.

Their meeting will come a week after Chang paid a visit to Washington and touted progress in US-Chinese military relations. But the Chinese general made clear that Beijing would staunchly defend its "core interests" and "maritime rights."

Chang's remarks underscored China's assertive stance on territorial rights in the South China Sea, which is believed to sit atop vast deposits of oil and natural gas.

Southeast Asian states have been trying for more than a decade to secure agreement from China on a legally binding code of conduct for the waterway.

China claims nearly all of the sea, even waters approaching the coasts of neighbouring countries. And Beijing has resisted agreeing to the code, wary of giving any concessions that may weaken its claim.

The United States has urged China and ASEAN members to agree on a code of conduct to defuse conflicts and said disagreements should be settled without "coercion."

Hagel will begin his trip on Thursday with a stop in Hawaii, where he will meet US troops and senior officers at Pacific Command. The Pentagon chief is then due in Kuala Lampur for talks on Saturday and Sunday, before flying to Jakarta on Monday and Brunei on Tuesday.

After the two-day ASEAN discussions, Hagel will wrap up his trip in Manila on August 29-30, where talks are expected to focus on US military assistance.

The United States has provided the Philippines with a decommissioned US coast guard cutter, which is used to patrol local waters also claimed by China.

US spy planes, P-3 Orion surveillance aircraft, also deliver crucial intelligence to Manila on China's naval activities in the South China Sea.