The government says it has terminated the contract of a senior trade officer, following revelations that he had allegedly accepted advantages without permission while in public office.

Responding to media enquiries, the Constitutional and Mainland Affairs Bureau confirmed that Ricky Cheng, a contract staff, has been relieved of his role as director of the SAR government's Tianjin Liaison Unit.

The bureau launched a probe after Cheng had earlier published a post on social media, describing his ferry seat upgrade on a trip to Macao.

"It has been considered that the incident... is suspected of breaching the provisions under the Prevention of Bribery Ordinance regarding civil servants accepting advantages without permission," a spokesman said on Wednesday night.

"The matter has already been referred to law enforcement agencies for follow up."