US Secretary of State Hillary Clinton arrived in Indonesia Monday hoping to encourage unity among Southeast Asian nations in an effort to manage increasingly tense disputes with China.

Clinton's last trip to the region in July was marred by the failure of the Association of Southeast Asian Nations to reach a consensus at talks in Cambodia, amid divisions in the 10-member group on how to treat a rising China.

The top US diplomat was scheduled to meet Indonesian Foreign Minister Marty Natalegawa shortly after arriving in Jakarta, and the following day will hold talks with President Susilo Bambang Yudhoyono and visit the headquarters of ASEAN, as part of her effort to promote ties with the economically dynamic and mostly US-friendly bloc.

She hopes "to get a sense of where we are and to get the Indonesians' advice about how we can be supportive, how we can put more wind into the sails of a diplomatic effort, which is what we all very much want", a senior US official said on her plane on customary condition of anonymity.

"The most important thing is that we end up in a diplomatic process where these issues are addressed in a strong diplomatic conversation between a unified ASEAN and China rather than through any kind of coercion," the official said.

Clinton, who made a refuelling stop in Brisbane, Australia, on her way from a South Pacific summit in the Cook Islands, will head to China on Tuesday for talks on the often uneasy relationship between the world's two largest economies.

The Philippines and Vietnam have both accused China of an intimidation campaign over territorial disputes in the South China Sea, a waterway through which half of the world's cargo sails.

Clinton, in a visit to Vietnam in 2010, buoyed Southeast Asian nations by declaring freedom of navigation in the South China Sea to be a US national interest, although she said that Washington would not take sides over disputes.

The United States recently issued an unusually strong warning to China after Beijing angered Southeast Asian nations by establishing a remote garrison in the South China Sea. China accused Clinton of seeking to "contain" its rise.

The official on Clinton's plane said the United States supported a recent statement of principles by ASEAN foreign ministers, who pledged unity and the early completion with China of a code of conduct for the South China Sea.

The United States has strongly encouraged work on a code of conduct, or COC, believing it is vital to preventing flare-ups from escalating. But Beijing has preferred to negotiate separately with ASEAN nations instead of dealing with a united bloc.

ASEAN Secretary-General Surin Pitsuwan cautioned that too much attention on the issue could prove counterproductive.

"We just hope that all the attention and the concern would not add to the fragility and instability over the issue. We want a conducive environment that would enable us to achieve the COC as soon as possible. As a major dialogue partner, the US certainly has a role to play and a contribution to make," he told AFP.

Clinton will later in the week visit Brunei, making her the first US secretary of state to visit all 10 ASEAN nations. Chinese Foreign Minister Yang Jiechi in August visited Indonesia and Brunei and took a conciliatory tone.

The administration of President Barack Obama, who spent part of his childhood in Indonesia, took office with a mission to expand relations with the world's largest Muslim-majority nation, seeing it as an ideal partner due to its embrace of democracy and historically moderate brand of Islam.

But momentum for closer relations has faltered, in part due to concern in the United States over recent mob violence by Indonesian Islamists against minorities.

The US official said Indonesia was still considered a "model of tolerance" but voiced alarm over "disturbing incidents" in recent months.

Clinton will "seek views with the Indonesian leadership on how they see things in the wake of those incidents and what the process is going forward to ensure that all communities feel safe and protected", she said.

Mobs have ransacked religious sites and attacked members of the Ahmadiyah Muslim sect along with Shiites and Christians.

Human Rights Watch has called on Clinton to press Indonesia to take "concrete steps" to address religious intolerance, saying that government policies and inaction were fuelling the violence.

In Jakarta some 500 Islamists staged a rally outside the US embassy to protest against her visit, complaining its goal was to advance American business interests, such as US mining giant Freeport McMoran's vast gold and copper mine in Papua province.