Five trees affected by redevelopment works in Kwun Tong have died or are dying because of poor handling by the Urban Renewal Authority, according to a green group.
The Conservancy Association says one of the "grossly mistreated" trees at the site of the former Kwun Tong government offices has died while four others seem likely to face a similar fate.
Transplanting of two trees was botched while others are not adequately protected from the construction work, association chief executive Ken So Kwok-yin said.
"The trees within the construction area have been grossly mistreated," he said. "The transplants were sloppy, and the tree care and monitoring standards are way below standard."
But the Urban Renewal Authority said the trees were in good health, despite dead leaves and branches, and were still adapting to their new environment after the transplants.
The two banyan trees which had stood in the car park of the old government offices had been moved to make way for a new building.
So said they were in conditions that indicated "a high chance of death".
Only 60 per cent of the original tree crowns remained and some 80 per cent of their roots had been cut off, he said.
"The trees have many dying branches and falling leaves, which indicates a high chance of death," he said.
"The new locations of the trees are full of concrete, metal wires and other construction materials."
The URA said the root balls of the trees had been trimmed before the transplant because large rocks had been found around them and the crowns were pruned to balance them in the interest of public safety.
The green group said another banyan tree standing in the middle of a construction area was inadequately protected.
A temporary structure built directly over the tree roots had "killed the tree alive", the green group said.
"All trees should have a tree protection zone as far as their tree crown under the current standards," it said.
In response, the URA said the tree in question had been transplanted last year to its new location specifically to cater for its asymmetric form.
"Sufficient soil depth has been provided for the tree and the main contractor has been reminded to carefully carry out adjacent building construction works to avoid branch damage," it said.
But So said the measures taken were not enough.
"The Urban Renewal Authority told us that they would value tree protection, but it seems like tree protection in this government site is worse than a lot of private construction sites."
Four banyan trees, a cotton tree and a spider tree were transplanted last year within the former Kwun Tong government offices site, according to the URA. The site is part of the of Kwun Tong town centre redevelopment - the city's biggest redevelopment project with a total site area of 570,000 square feet.