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Investors can exchange the seven-year zero-coupon bonds for shares of China Petroleum, better known as Sinopec, at a premium of as much as 50 percent to the stock's closing price of HK$7.17 on Monday. Trading in the shares was halted pending the announcement, Bloomberg News said.

Sinopec bought outstanding shares in four listed units last year, prompting speculation it will buy out other units including Sinopec Shanghai Petrochemical Co. The company is luring investors with rising share prices to sell debt that pays no interest. The shares gained 46 percent in the past year, compared with a 25 percent increase in the Hang Seng Index.

"Convertible bond is the best option for Sinopec to raise funds considering how bullish the market sentiment is at the moment for China equities," said Gordon Kwan, research director of China oil and gas at CLSA Ltd in Hong Kong.

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