The Guangdong branch of the China Petroleum and Chemical Corporation (Sinopec), China's biggest supplier of petrol, is being attacked for reportedly spending more than 1 million yuan (US$153,000) on high-end liquor.

The news immediately made a splash online where Internet users have long complained about the high price of oil in China and the oil giant's extremely large profits.

In light of the online tirade of criticism, Sinopec said in a statement on Thursday it had sent a team to probe the alleged purchases and promised to publish the results of the investigation as soon as possible.

The statement said those responsible will be punished if they are found to have violated any laws or Party discipline.

The alleged purchases by Sinopec Guangdong were revealed online on Monday, along with photographs and images that were said to be photocopies of invoices.

The invoices appeared to show that the company bought luxury alcohol on three occasions for an overall price of 1.15 million yuan in September 2010. The order seemed to show that the company bought Moutai, which is one of the most famous and expensive liquor brands in China.

A bottle of Moutai that has been stored for 50 years sells for about 22,000 yuan while non-vintage Moutai sells for more than 1,000 yuan a bottle.

The online postings seemed to show that Sinopec Guangdong had bought 30 bottles of Moutai that had been stored for 50 years, another 30 bottles of Moutai that had been stored for 30 years, and 60 bottles of Moutai that had been stored for 15 years, in addition to 360 bottles of non-vintage Moutai.

Another picture of a photocopy of an undated purchase contract showed that the company had bought a total of 696 bottles of imported alcohol costing 630,720 yuan. The imported alcohol included 17 bottles of Chateau Lafite Rothschild produced in 1996, which is priced at more than 10,000 yuan a bottle.

The online posting claimed Lu Guangyu, general manager of Sinopec Guangdong, ordered these liquors and planned to use them at banquets or give them out as gifts.

The company on Tuesday confirmed the purchases, but Xu Tao, the company's spokesman, said the alcohol was destined to be resold at stores at Sinopec's gas stations.