HONG KONG - Chinese companies hounded by debt obligations accrued over the past few years are grappling with a new adversary at what is a very inconvenient time: global ratings agencies.

Standard & Poor's and Fitch Ratings have slashed more ratings of Chinese companies in 2014 than a year earlier as towering debts weigh on corporate bottom-lines. The thumbs-down from the agencies will make it harder - and more costly - for companies to borrow at a time when their cash flows are taking a hit from a weakened economy.

Analysts say big companies backed by the Chinese government are less likely to be at risk than smaller, independent firms that had binged on the easy credit springing from a round of government stimulus in 2008-2009.

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On Monday, S&P cut the ratings of China Shanshui Cement and Guangzhou R&F Properties by a notch, plunging them deeper into junk status. Last week, fellow rating agency Moody's downgraded steelmaker China Oriental, already wallowing in non-investment territory, also by a notch.

"When the economy is deleveraging and credit is not growing as fast as before, they need extra cash to repay debt instead of refinancing it in the market, thereby creating pressure on balance sheets and in some cases on the ratings," said Moody's analyst Ivan Chung.

Data released over the weekend showed factory output grew at its slackest pace in six years in August, stoking fears that China's economy was sliding deeper into a downturn.

Analysts say the steel, metals, chemicals sectors and real estate developers in some cities will find it difficult to raise cash as excess capacity heaps pressure on their credit profiles.

A debt-infused expansion at Guangzhou R&F Properties in a now weaker market and tighter credit environment led S&P to downgrade its rating to BB-minus from BB. Its debt-to-earnings before interest, taxes, depreciation and amortisation (EBITDA) ratio rose to 5.05 at end-2013 from 3.12 in 2011.

S&P also cut China Shanshui Cement to B-plus from BB-minus, saying it expected limited improvement in cash flow because of subdued cement demand on account of the economic slowdown and overcapacity. Its debt-to-EBITDA ratio more than doubled to 4.56 at end-2013 from 2.06 in 2011.

Moody's lowered its rating on China Oriental to B2 from B1, saying reduced lending to the steel industry could hurt access to fresh bank loans.

China Oriental, China Shanshui Cement and Guangzhou R&F Properties did not immediately respond to Reuters requests for comment.

Earlier this month, Fitch cut its outlook on oil and gas field services provider Anton Oilfield to negative from stable, blaming the squeeze on its margins from competition, reduced capital spending by customers in China and a longer working capital cycle that was hurting its cash flow.