Conservation authorities said on Monday corals close to a Unesco-listed geopark in Sai Kung would not be heavily impacted by a surge of visitors during the National Day Golden Week holiday.

Officials from the Agriculture, Fisheries and Conservation Department also pledged to further monitor the coral outcrop near Sharp Island for anything unusual, following reports of tourists damaging the marine life there.

Some travellers to the island reportedly captured marine organisms, trampled on corals and cooked on the beach.

"We will arrange for our officers to go underwater and monitor the coral zone as soon as possible to assess the situation," said deputy director Patrick Lai.

"There's quite a bit of distance between the coral zone and the beach on Sharp Island, so the impact on the coral zone is unlikely to be significant."

The number of people visiting the island on October 1 was said to reach 4,000, which Lai said was higher than what authorities initially estimated.

On calls to limit visitor numbers to the island, Lai said officials were open to all suggestions and would take a look at what measures could be implemented.