BEIJING (Reuters) -Chinese leaders pledged on Thursday to modernise the country's industrial complex, expand domestic demand, curb debt and property sector risks, as well as implement financial and fiscal reforms, state media said after a key Communist Party meeting.

The official news agency Xinhua's readout of the meeting, which takes place roughly every five years, also said Beijing wanted to improve social security, healthcare and income distribution systems and introduce land reforms.

The report said China will "enhance the role of market mechanisms in the economy, create a fairer and more dynamic market environment and optimise the efficiency of resource allocation."

The previous wording in official documents was that markets would "play a decisive role" in the economy.

"Restrictions on the market will be lifted, while effective regulation will be ensured to better maintain order in the market and remedy market failures," said the report.

The meeting readout did not say what changes will be implemented, but said the "tasks" should be completed by 2029.

A document with more detailed policy plans presented at the four-day, closed-door meeting of Communist Party central committee members led by President Xi Jinping, is expected to be released in coming days.

Previewed by state media as "epoch-making," the event, known as a plenum, took place at a time of financial hardship for an increasing number of Chinese at home and of heightened adversity against the country's industrial policies abroad.

The communique re-emphasised China's quest for "new productive forces", a term coined by Xi last year that envisions scientific research and technological breakthroughs that could modernise manufacturing and kickstart a new era of high growth.

"We will improve the institutions and mechanisms for fostering new quality productive forces in line with local conditions," it said.

The world's second-largest economy grew at a slower than expected pace in the second quarter, leaning hard on industrial output and external demand, while the crisis-hit property sector and household consumption continued to disappoint.

China pledged to resolve the deepening imbalance between high investment and output levels and tepid demand more than a decade ago at a similar plenum. However, rather than directing resources towards consumers, it poured money into infrastructure and real estate, accumulating debt at an unsustainable pace.

Thursday's communique reiterated China wanted to "actively expand domestic demand."