Taxi licences have all along given cabbies "exclusive rights" to operate, Chief Executive John Lee said on Tuesday in response to a proposal from the trade for the government to consider repurchasing licences that it said have depreciated in value.

Some within the taxi industry are calling on the administration to buy back licences for HK$5 million each, saying their value had dropped due to competition from online ride-hailing services.

When asked about the suggestion, Lee said the administration has to move with caution where public money is concerned and urged the taxi sector to improve the quality of services rendered amid "a lot of voices and opinions" about cabbies not reaching standards expected.

He went on to say that the licences allowed the sector to have "privileges" in operating the vehicles, such as the use of taxi stands and the right to pick up passengers in designated restricted areas and from the street.

"These are the privileges granted to taxis under the relevant taxi licences," Lee said.

"That's why there's a [direct] return from taxi licences, and taxi operators have been making a profit over a prolonged period with taxi licences."

Lee said online ride-hailing was an "irreversible" global trend and that the government is carrying out a study on establishing a regulatory framework for such platforms to specify what type of point-to-point transfer will be considered illegal.

"The Transport and Logistics Bureau is working hard and studying all details in relation to the legal framework," he said.

"The details will eventually be announced.

"I hope that, by then, the public and the Legislative Council will debate all these issues fully so that we can come up with a proper regulatory framework for online ride-hailing platforms and services."