Hong Kong (CNN) A United Kingdom consular worker who was detained in China for 15 days has returned to Hong Kong, according to his family.

Simon Cheng was detained by Chinese authorities after traveling to the mainland Chinese city of Shenzhen, two weeks ago. In a statement Saturday morning, his family said the 28-year-old Hong Konger had returned home.

"Simon has returned to Hong Kong; thanks you everyone for your support!" read a post on a Facebook page set up following his disappearance and authorized by his family. "Simon and his family wish to have some time to rest and recover ... We will explain more later."

Police in Luohu, a district of Shenzhen, confirmed Cheng's release on Saturday. He was freed "upon completing his term of detention" on August 24, police said in a statement posted to social media.

It remains unclear exactly why he was first detained. China's Ministry of Foreign Affairs (MOFA) had said he would be held for 15 days under administrative detention for violating China's Security Administration Punishment Law, which covers a range of offenses deemed too minor to be crimes.

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