Companies that connect China's wealthy gamblers to Macau's casinos are waiting as long as a year for gamblers to repay billions of dollars of loans, crippling the business model of an industry that sustains the world's biggest casino center.

These "junket" businesses, which lend to high rollers and operate private gambling rooms, normally collect within 30 days and charge interest rates as high as 3 percent per month on overdue balances, according to Macau-based junket consultant Tony Tong.

Now the junkets are on the hook for a surge in bad debts as China's economic slowdown and a corruption crackdown keep some VIP gamblers away. With little access to credit and slow repayments, the money isn't flowing.