* Maritime disputes shadow U.S.-China ties
* Clinton visit comes at moment of political transition
* China Foreign Ministry suggest U.S. role not helpful in sea dispute
By Andrew Quinn and Chris Buckley
JAKARTA/BEIJING, Sept 4 (Reuters) - China warned the United States not to get involved in South China Sea territorial disputes on Tuesday as U.S. Secretary of State Hillary Clinton arrived in Beijing pledging to pass on a strong message on the need to calm regional tension.
The last time Clinton visited the Chinese capital, plans to highlight improving U.S.-China ties were derailed by a blind Chinese dissident whose dramatic flight to the U.S. embassy exposed the deeply uneasy relationship.
The irritants this time are disputes over tiny islets and craggy outcrops in oil- and gas-rich areas of the South and East China Seas that have set China against U.S. regional allies such as the Philippines and Taiwan.
U.S. officials say the message is once again one of cooperation and partnership - and an important chance to compare notes during a year of political transition.
But the unease remains, sharpened by disputes in the South and East China Seas that have rattled nerves across the region and led to testy exchanges with Washington just as the Obama administration "pivots" to the Asia-Pacific region following years of military engagement in Iraq and Afghanistan.
Chinese Foreign Ministry spokesman Hong Lei suggested at a daily news briefing that Washington was not a helpful force in the maritime disputes.
"We have noted that the United States has stated many times that it does not take sides," he said when asked about the U.S. role. "We hope that the United States will abide by its promises and do more that is beneficial to regional peace and stability, and not the opposite."
Chinese newspapers, including Communist Party mouthpiece the People's Daily, have suggested the South China Sea territorial claims are among Beijing's "core national interests" - a term suggesting they share the same importance as sovereignty over Tibet and Xinjiang.
Hong did not directly answer a question about whether that was the government's official position.
"China, like any other country in the world, has the duty to protect its sovereignty and territorial integrity," he said.
Clinton arrived in Beijing late on Tuesday, huddling with U.S. officials on board her plane before heading off to meetings with Foreign Minister Yang Jiechi followed by a dinner.
In Jakarta on Monday, she urged China and its Southeast Asian neighbours to move quickly on a code of conduct for the South China Sea and stressed that disputes should be resolved "without coercion, without intimidation, without threats and certainly without the use of force"..
But progress has been thwarted in recent months by China's increasingly assertive posture, which has included establishing a garrison on a disputed island and stepping up patrols of contested waters.
That suggests Beijing has no intention of backing down on its unilateral claim to sovereignty over a huge stretch of ocean and potentially equally large energy reserves.
Clinton faces a balancing act, pushing on the territorial disputes while keeping cooperation on track on other issues including reining in the North Korean and Iranian nuclear programmes, the Syria crisis and economic disputes that have long bedevilled the two countries.
"One of the challenges before us is to demonstrate how we deal with areas in which we have different perceptions and where we face challenging issues on the ground, or in this case on the water," one senior U.S. official said.
But some Chinese media have been blunt in their opposition to Clinton. The Global Times, a popular, nationalist tabloid, accused her of "deeply intensifying mutual suspicion".
"Many Chinese people dislike Hillary Clinton," it said in an editorial. "She has brought new and extremely profound mutual distrust between the mainstream societies of the two countries, and removing that will not be easy."
Clinton on Wednesday will meet outgoing President Hu Jintao and Vice President Xi Jinping, the man who will likely succeed him as paramount leader following a Communist Party congress this year.
Xi visited the United States in February on a get-acquainted tour and U.S. officials expect him to be a steady-handed leader.
But concerns over China's fast-expanding influence and its belligerent tone in the regional disputes have Washington scrambling to assess how Beijing's political stars are lining up.
China, too, has its concerns and has pushed back against U.S. attempts to referee the South China Sea dispute and insert itself into similar rows between China, Japan and South Korea over islands in the East China Sea.
While Washington has stressed that it takes no position on the competing claims and simply wants to see a mechanism established to resolve them, its forceful calls on China to play along have had a cool reception in Beijing.
Mark Valencia, a Hawaii-based expert on Asia-Pacific maritime disputes, said the recent exchanges left "no doubt that the U.S. is siding with ASEAN (Association of Southeast Asian Nations) -- not necessarily saying that their claim is correct, but that the bases of their claims have more merit than those of China".
During Clinton's last China visit in April, dissident Chen Guangcheng stole the headlines with his made-for-TV escape from house arrest, flight to the U.S. embassy and eventual decision to take a U.S.-brokered deal to travel to New York.
U.S. officials are hoping for no such surprises during Clinton's 24-hour visit, saying this is a moment for stability, not stirring the waters.
"I think the secretary intends very clearly to underscore our continuing interest in maintaining a strong, positive relationship," the senior U.S. official said.