BEIJING, July 28 (Reuters) - China's central bank said on Tuesday that it will use various monetary tools to maintain appropriate levels of liquidity in the second half of this year .

It added that the country's main economic indicators are steadily improving.

Plunging share markets have added to concerns about the health of the world's second-biggest economy, rattling global financial markets.

China's factory sector contracted by the most in 15 months in July as shrinking orders depressed output, a preliminary private survey showed on Friday, a worse-than-expected result that comes on the heels of a stock market crash which began in June.

(Reporting by David Stanway and Ben Blanchard; Editing by Kim Coghill)