Former environment chief Wong Kam-sing on Tuesday expressed support for the waste charging scheme and called on people to treasure the opportunity to help Hong Kong reduce waste.

Wong's comments came after former vice chairman of the All-China Federation of Returned Overseas Chinese, Lo Man-tuen, said the initiative was proposed by "radical opposition" and that it was "an impossible mission".

The former minister said previous administrations - including himself - had pushed for the policy with a lot of support from the community, and now society should overcome challenges that arise from the scheme's trial.

Wong added it takes time for people to change their habits and the administration should not make any hasty decision based on the feedback collected in just a few weeks.

"Wouldn't we be letting our young people down if we missed this opportunity?" he asked.

"We should convey a message to young people that we have to consider the economy and environment together, that we have to support sustainable development and follow the national policy. 'Clear waters and green mountains are as valuable as gold and silver mountains.'"

He noted the waste charging policy would give people an incentive to recycle, and allow the recycling facilities in the territory to be utilised.

Meanwhile, Baptist University's emeritus biology professor, Jonathan Wong, said Hong Kong cannot wait until it is fully ready to roll out the pay-as-you-go scheme.

"We cannot implement the law [on the waste charging scheme] only when we have a perfect plan. No place in the world does that," he said.

"I think now isn't the time to think about delaying the policy or not. Instead we should think about how to carry this out, and have a good demonstration in the community so that we can help people solve their problems in different types of housing and commercial settings."