BEIJING, Oct 23 (Reuters) - China's Communist Party elite vowed on Thursday to build a modern industrial system and make more efforts to achieve technology self-reliance, moves it sees as key to bolstering its position in its intensifying rivalry with the United States.

As expected, the Party's Central Committee also promised more efforts to expand domestic demand and improve people's livelihoods - long-standing goals that in recent years have been little more than an afterthought as China prioritised manufacturing and investment.

The Chinese economy's overreliance on exports at a time of heightened trade tensions with Washington might push Beijing to find a better policy balance in coming years, although analysts expect efforts to be slow.

A communique from state news agency Xinhua after the Party leaders' four-day closed door meeting, known as a plenum, outlined China's priorities in its next five-year development plan, which will only be released in full at a parliamentary meeting in March.

"The country will be in a period (2026-2030) where strategic opportunities coexist with risks and challenges, and there will be an increase in uncertain and unpredictable factors," Xinhua reported, citing the communique.

"We should maintain a reasonable proportion of the manufacturing sector and establish a modern industrial system with advanced manufacturing as its backbone."

The communique said Beijing will strive to improve people's welfare and the social security system, but did not provide details on how Beijing intends to achieve that or where the funds would come from.

Uncertainty over the timing, pace, funding and size of such policies are likely to keep economists and investors concerned over the government's ability to rebalance an economy in which household consumption lags global averages by about 20 percentage points of GDP.