* ASEAN summit is being held in Bangkok
* Trade will be the main topic, diplomats say
* Little discussion of regional problems expected
By Panu Wongcha-um and Patpicha Tanakasempipat
BANGKOK, Nov 2 (Reuters) - Southeast Asian leaders are expected to voice concern at rising trade tensions during a regional summit starting on Saturday in the shadow of the U.S.-China trade war and amid worries at U.S. disengagement from the region.
The 10 countries of the Association of Southeast Asian Nations (ASEAN) will meet in Bangkok, where they will also hold talks with representatives of world powers and have discussions on a regional trade agreement backed by Beijing.
A draft final summit statement seen by Reuters said the leaders would express "deep concern over the rising trade tensions and on-going protectionist and anti-globalisation sentiments."
Trade would be the main topic, diplomats said, with little discussion expected on perennial regional problems such as maritime disputes with China over the South China Sea and the plight of Rohingya refugees driven from Myanmar.
Southeast Asian states are at the sharp end of the trade war, with growth expected to slow to its lowest in five years this year. They are also worried at increasing Chinese influence in a region whose population of 620 million is less than half of China's.
The United States, an important trade partner, is sending a delegation to the meetings. But the downgrading of its delegation compared to those in previous years and to those of other countries has concerned those who saw Washington as a security counterweight to Beijing. of President Donald Trump or Vice President Mike Pence, the United States will be represented by Commerce Secretary Wilbur Ross and White House national security adviser Robert O'Brien. China is sending its premier, Li Keqiang.
"The U.S. is signalling that the ASEAN Summit and related meetings are not as important as other countries are considering them to be," Kantathi Suphamongkhon, former Thai foreign minister told Reuters. "This signals that the U.S. is a lesser player in our area."
WORLD'S BIGGEST TRADE AREA
Southeast Asian states hope to make progress on what could become the world's biggest free-trade area - the China-backed Regional Comprehensive Economic Partnership (RCEP) - comprising 16 countries that account for a third of global gross domestic product and nearly half the world's population.
Discussions on the agreement have continued since 2012 and have accelerated during the trade war, but tough issues remain - including Indian apprehension over giving China greater market access.
The Thai hosts of the summit have said they hope talks on the agreement will be concluded this year, but a news conference on progress among RCEP ministers was cancelled late on Friday without explanation.
"The finalization of the RCEP negotiation has become a key test for ASEAN's capacity to deliver on its often-cited centrality," Marty Natalegawa, a former Indonesian foreign minister, told Reuters.
Human rights groups said they did not expect the Southeast Asian countries would do much to address problems such as the Rohingya refugees or discuss questions such as the growing authoritarianism in some member states.
"The human rights and democracy battleground is being lost in ASEAN and it's consequential because it will play into the hands of the more authoritarian China ... especially when you have the US under Trump non-committal, not showing up," Thitinan Pongsudhirak, a scholar at Bangkok's Chulalongkorn University, told Reuters. (Editing by Matthew Tostevin and Timothy Heritage)