The government has brushed aside concerns that plans for artificial islands off Lantau will prove difficult to complete, after it emerged that the waters there are deeper than those where previous major reclamation projects took place.

Green groups have said the HK$580 billion Kau Yi Chau artificial islands development might face engineering hurdles because the sea there is 1.5 times deeper than originally thought.

But Michael Fong, director of Civil Engineering and Development, said on Thursday that reclamation for the building of an incinerator was completed in even deeper waters nearby, with the help of new technology.

“So we have full confidence that with the adoption of the latest technology, what we call ‘deep cement mixing’ construction method, we’ll be able to complete the Kau Yi Chau artificial islands successfully and smoothly.”

Fong said that a Y-shaped water channel between the three artificial islands will be wide enough to minimise the impact on the natural habitat for species like stony corals.

"The water channel will be slightly wider than the Shing Mun River in Sha Tin," he said. "We've built a comprehensive and thorough computer model on the water flow, and preliminary results shows a water channel with a width of 200 metres will be enough to maintain the present water flow."

The official also said authorities are considering whether a railway line to connect the islands to Hong Kong Island should have a stop at Kennedy Town, in addition to the planned interchange at HKU Station.