WASHINGTON, Aug 9 (Reuters) - United States President Joe Biden is unlikely to attend summits with Southeast Asian leaders in Jakarta next month, multiple sources told Reuters, an absence that would raise questions about US commitment to a region vital in its efforts to push back against China's expanding influence.

Biden is due to attend a Sep 9 to Sep 10 G20 summit in India and said on Tuesday (Aug 9) he plans to visit an important emerging Southeast Asian partner Vietnam "shortly" to upgrade ties, but his presence at the Sep 4 to Sep 7 summits of the 10-nation Association of Southeast Asian Nations (ASEAN) is in significant doubt.

One source close to the matter said Biden would not go to Indonesia, and another cited a Washington-based ambassador from an ASEAN member as saying that Indonesia had been informed on Monday that Biden would not be going. Other sources cited White House officials as saying that Biden's attendance was "unlikely".

Asked if it was correct that Biden would not be going to Indonesia, a senior White House official told Reuters on Tuesday: "We're still working on it ... We'll probably have more to say about it soon."

White House spokespersons did not immediately respond to a request for comment. Sources said Biden's schedule for Asia is not official until it has been announced and could change.

Several ASEAN diplomats said it would be a significant disappointment if Biden did not go to Jakarta, given the public emphasis his administration puts on the importance of ties with the region.

One senior diplomat referred to Indonesia having scheduled the ASEAN summits, which are normally held in November, for September, specifically to make it possible for Biden to attend and then go on to the G20.

Sources said Biden was expected to send Vice President Kamala Harris in his place. Harris, the first Asian American vice president, has conducted diplomacy in the region before.