The Ombudsman has launched an investigation into the Development Bureau's handling of complaints regarding trees on government land.

In a statement published on Thursday, the office said that from 2019 to 2021, the government's 1823 hotline received more than 20,000 tree-related complaints per year.

Data from the hotline showed that as of March this year, there was a backlog of more than 2,000 tree-related complaints, of which 80 percent had dragged on for 90 days or longer.

The Ombudsman's office itself received around 120 complaints in the past five years concerning tree management.

According to the office, the government uses an "integrated approach" for managing trees on government land, whereby government departments manage trees in their area, and the Tree Management Office (TMO) under the Development Bureau co-ordinates the tree management work of various departments.

"Some tree-related complaints remained unresolved for too long. If not promptly addressed, problematic trees may cause environmental nuisances or even pose potential hazards to public safety," said Ombudsman Winnie Chiu.

Chiu said the investigation will look into whether the TMO and Development Bureau have supervised the handling of tree complaints effectively, and whether there is a "clear delineation of tree management responsibilities among departments".

Her office said it welcomes submissions from members of the public on the matter, between now and November 6.