Environment chief Tse Chin-wan has stressed that a ban on single-use plastics is not meant to trouble people, saying prices for alternatives will go down further when they become more common.

The first phase of a citywide ban on single-use plastics took effect on April 22, prohibiting the sale and use of disposable polystyrene utensils, plastic straws, stirrers, cutlery and plates.

Tse told RTHK's "Your Home Address" programme, which was broadcast on Saturday, that the policy is not intended to make people's lives more difficult but to regulate plastics at source.

"For those disposable tableware, if you switch to the alternatives, the difference is actually very small, usually one or two cents to a maximum of 50 cents for the whole package. Therefore, it's not very expensive," he said.

"We expect that as more and more will be used in society, the price will go down further. People's behaviour will drive the development of the alternatives, as well as drive down the price of those alternatives."

The minister also said authorities must find reliable substitutes before expanding the scope of scheme, as he ruled out imposing a blanket ban on plastic products because their use is too widespread.

"We are not going to ban the use of all plastics at once. That is not possible... We start with those which we already have readily available and mature alternatives," he said.

On the postponed municipal solid waste charging scheme, the environment minister said there are proven effects of the policy in Seoul, where the amount to garbage produced was cut by 60 to 70 percent in about five to 10 years.

The government pushed back the implementation of the waste charging to August, while it held trials for the scheme at more than a dozen premises this month.