A group of minibus drivers on Monday said they fear they will be put out of business by a more expensive toll for using the Cross-Harbour Tunnel.

Under a government scheme to equalise tolls at the three harbour crossings, the price for driving a minibus through the tunnel between Causeway Bay and Hung Hom will rise next month from HK$10 to HK$50.

"This is a blow to us and will leave red minibuses unable to operate," said Chan Fung-yuen, who heads the public light bus branch of the Motor Transport Workers General Union.

"If we transfer the additional cost to passengers, we will lose our competitiveness and go out of business. We work five round trips during each shift, and the tunnel toll will cost HK$500 [a day]... how much money can we earn?"

Chan said the fee should be halved to HK$25, the same as the price for taxis.

In Legco, however, a transport official defended the planned new toll fee.

"Actually we haven't adjusted the toll at the Cross-Harbour Tunnel in the past 39 years, which has been at a very low level," said Acting Commissioner for Transport Patrick Ho.

"The toll level we're setting is close to the mean value of the three tunnels currently, so we think HK$50 is a reasonable level."

The government said it will review the harbour crossing tolls again in 2025.