BEIJING -- "Triangular debts", a liquidity problem resulting from payment delays between companies, are posing a threat to businesses in China's iron and steel, machinery and coal sectors, analysts have warned.

Compounded by a slowing economy, tightened monetary supply and lackluster business performance, the lurking debt risk, which once hit China in the 1990s, could take a huge toll on the real economy.

One recent case of a company weighed down by triangular debts revolved around Maanshan Iron & Steel Co Ltd, an industrial giant in East China's Anhui province.

The company announced at the end of September that its subordinate logistics company had filed 23 lawsuits against suppliers that could not pay back their debts.

A couple of weeks later, the company itself filed a restructuring application because it was also unable to pay back a pile of debt owed to downstream clients.

According to Wind, a leading China-based economic database, the turnover of listed companies on the A-share market rose by 8 percent year-on-year in the first half of 2012, whereas their accounts receivable surged by 37 percent year-on-year to stand at 2.2 trillion yuan ($349.15 billion).

By the end of June, as much as 18.6 percent of their business revenues came from items that were purchased on credit, with payments not yet received, Wind's data showed.

In the machinery industry, the problem of collecting debts is "not only between manufacturers and agents", said Qi Jun, an analyst at the China Construction Machinery Association. "Many manufacturers are defaulting on payments to their component suppliers."

Between industries, the liquidity problem may also spread from downstream sectors upward.

As the primary suppliers of machinery manufacturers, steel companies are also having a hard time. China's major steel enterprises have seen their accounts receivable exceed 50 billion yuan so far this year, but the amount they have to pay stands at some 300 billion yuan.

Likewise, the coal industry, which itself has suffered from overcapacity and price slumps since the beginning of 2012, is waiting for steel companies to pay in order to stay afloat.

The cash flow problem now involves more small and medium-sized enterprises, said an analyst with the Development Research Center of the State Council who declined to be named.

A report released in mid-October regarding financing for SMEs in the Yangtze River Delta showed that over half of the SMEs in the region were cash-strapped, while about 30 percent have had operational difficulties due to clients' defaults on debts in the last six months.

SMEs usually do not have much say in negotiations with larger companies, and as suppliers of raw materials and components, the final lenders, they have to bear the brunt of triangular debts, industry insiders said.

Earlier media reports said authorities, including the Ministry of Industry and Information Technology and the Ministry of Commerce, have initiated joint probes into the debt risks.