Image caption Mr Xue says interrogators burned his arms with cigarettes

A Chinese-born American geologist has been sentenced to eight years in jail in China for stealing state secrets.

Xue Feng, 44, was detained in 2007 after negotiating the sale of an oil industry database to his employers, an American consultancy company.

Mr Xue said the information he had acquired about China's oil industry was publicly available. He claimed he had been tortured while in detention.

The US embassy said it was "dismayed" and called for his immediate release.

ANALYSIS Xue Feng's punishment follows the 10-year sentence given in March to Stern Hu, formerly of mining firm Rio Tinto, for accepting bribes and dealing in state secrets. So are there lessons to draw? It seems so. First, what is a secret in China? The definition may be vague, but both cases show how sensitive China is about information relating to its state firms, particularly in strategic resources sectors. Xue Feng was dealing in oil, Stern Hu in iron and steel. Second, China also seems to be extremely sensitive if you're Chinese-born but go abroad, get a passport and then return to work for a foreign firm. Men like Xue Feng and Stern Hu can make contacts, build relationships and get access to information inside China that no foreigner can. They can be invaluable to foreign firms. There are more and more Chinese like them and China seems to see them as a threat. Both men found that their passports, American for Xue Feng and Australian for Stern Hu, offered little protection. US President Barack Obama raised Xue Feng's case, Australia raised Stern Hu's. But China delivered harsh sentences anyway. Their fate appears to send a clear warning: Information about China's resources and the commercial dealings of its state firms is jealously protected and if you acquire such information and you are Chinese-born don't expect your foreign passport to shield you.

The jail term handed down was described by his lawyer as "very heavy". Mr Xue was also fined 200,000 yuan (£19,500; $30,000).

Mr Xue's crime was to arrange the sale of an openly available database about China's largely state-controlled oil industry to his US consulting firm IHS Energy, now known as IHS inc.

The geologist has claimed that interrogators burned his arms with cigarettes and hit him on the head with an ashtray.

The US Ambassador to China, Jon Huntsman, was at court for the sentencing, in a show of high-level US concern over the case.

The embassy later issued a statement saying it was dismayed and urged China to grant Mr Xue "humanitarian release and immediately deport him".

Three Chinese nationals were also sentenced for illegally providing intelligence abroad.

Li Yongbo was sentenced to six years in jail, and Chen Mengjin and Li Dongxu were both given two-and-a-half-year sentences.

The BBC's Damian Grammaticas in Beijing says that after this case foreign businesses in China are likely to tread even more warily when dealing with information about state firms.

Draft regulations released by China's government earlier this year defined business information held by state firms as state secrets.

Legal observers have also voiced concern that China's courts are ignoring legal procedures when dealing with sensitive cases.

In Xue Feng's case the two-and-a-half-years it has taken to reach a verdict they say breaches China's own legal time limits.