Washington, July 7 (DPA) The US called on China Tuesday to release a US geologist who was sentenced to eight years in prison for obtaining an oil database regarded as a state secret.

Xue Feng, a Chinese born US citizen, received the sentence Monday along with a fine of nearly $30,000. Mark Toner, a spokesman for the US State Department, said the sentence was disturbing.

"We remain extremely concerned about his right to due process under Chinese law," Toner said. "We call on China to grant Xue humanitarian release and immediately deport him back to the United States."

A court in Beijing found Xue, 44, guilty of trying to "obtain and traffic state secrets" by buying the database on China's oil industry, which was only classified as a state secret after his arrest in November 2007, according to the Dui Hua Foundation, a US-based rights group.

Xue and his employer, US energy and engineering consultants IHS, said they believed the database was a commercially available product, the foundation said.

Xue was tried in July last year but the court repeatedly delayed its verdict in the case, which US President Barack Obama raised with Chinese leaders during a visit to Beijing in November.

US Ambassador Jon Huntsman attended Monday's sentencing of the naturalized US citizen.