Hong Kong authorities are searching for a 28-year-old man who went hiking and lost contact with his family after a dispute with his girlfriend, with a helicopter deployed to aid in the operation.

Police said on Saturday that they received a report at 11.30am from a man who said his younger brother had lost contact with his family after arguing with his girlfriend the evening before.

The caller added his brother last posted on social media that he was hiking along the fourth section of the MacLehose Trail, prompting officers to search the area around Lion Rock and Tsz Wan Shan, the force said.

But the man had yet to be found, police added.

The Fire Services Department said its officers had assembled at Fat Jong Temple in Tsz Wan Shan, with an ambulance still on standby.

A Government Flying Service helicopter was deployed at one point to aid in the search, it added.