China is the world's second largest oil consumer

The firm, which already has a Hong Kong listing, did not say how much its China mainland flotation, due on 5 November, was likely to fetch.

But based on its Hong Kong share price, the offering would beat the previous $8.9bn record set by Shenhua Energy.

Separately, Chinese e-commerce firm Alibaba.com plans to list in Hong Kong.

PetroChina's shares in Hong Kong have shot up by more than 25% this month in anticipation of its listing on China's mainland stock market.

Warren Buffett's investment company, Berkshire Hathaway, capitalised on these gains, selling shares in the oil giant on Friday and making a $3.5bn profit.

Domestic demand

The state-run Chinese firm is the latest major corporation to seek a share sale in Shanghai, prompted by rising demand for equities from private domestic investors, who cannot buy shares overseas.

It follows the flotation of China's biggest coal miner, Shenhua Energy, which saw its shares surge 87% on its first day of trading earlier this month.

Beijing-based China Construction Bank also had a very favourable response to a fundraising and flotation in September.

Flotations in mainland China have raised about $40.5bn in 2007 so far, almost double that for the whole of 2006. As a result, Shanghai shares have been soaring over the past 10 months.

Analysts expect PetroChina, owned by China National Petroleum, to use the money from its share sale to fund expansion abroad, as supplies have been slowing at its existing domestic wells.