The disciplinary body of east China's Shandong Province is investigating an agriculture official after his hand-written promise to his mistress that he will divorce his wife was posted online.

Shan Zengde, vice head of the Agricultural Department of Shandong provincial government, is under disciplinary investigation by the Shandong Provincial Commission for Discipline Inspection of the Communist Party of China, it has been confirmed.

"According to the preliminary investigation, Shan's 'divorce promise' to his mistress is basically true," sources with the provincial government told Xinhua on Friday.

Shan allegedly promised his mistress, Su Chunyuan, that he would divorce his wife, Zhang Fengyun, within the period between Nov. 21 and Dec. 20 and then marry Su.

It is unknown how Shan's written promise found its way online.

Shan's signature and his fingerprint can clearly be seen on the document, images of which are being widely reposted in China's cyberspace. The promise was written on Nov. 21.

Shi Fang, vice director of the general office at the agriculture department where Shan is working, signed his name on the document as a witness.

Shan is the latest of an array of Chinese officials to be investigated after being implicated in sex scandals or corruption by netizens.

Also this month, Lei Zhengfu, the top official of a district in southwest China's Chongqing Municipality, was removed from his post after the local disciplinary body confirmed he was the man featured in a sex video widely circulated online.