The amount of plastic bottle waste collected from separation bins under a government subsidy scheme has doubled in seven months.
The weight of bottles collected from 250 housing estates rose from 8,481kg in April to 17,844kg in November under a trial scheme to boost recycling rates.
But the waste was seldom screened and sorted according to its type before being shipped to the mainland for processing, said Ng Ting-leung, director of the Conservancy Association.
As a result, the shipments were likely to contain unwanted waste that could not be properly recycled and would have to be dumped in landfill sites across the border.
'The mainland recycling facility might not be very advanced,' said Mr Ng.
'If we could control the plastic waste better on our side, we could help minimise unnecessary pollution and waste on the mainland.'