A report 15 years ago warned of potential dangers at the location of Monday's ferry disaster, it was revealed last night.
The survey came to light as another unpublished report, completed before the Lamma tragedy, predicted more people would be injured or killed in Hong Kong waters as passenger-carrying vessels get bigger and faster.
The reports emerged at a time when the number of passenger-carrying vessels is expected to increase further when the Kai Tak cruise terminal comes into operation next year.
The 1997 report found that while there were "very few incidents" in and around the East and West Lamma channels, the area was home to "local situations that warrant attention".
It continued: "These include returning pleasure craft [vessels that carry up to 60 people] from either Lamma or Lantau Islands to Aberdeen Harbour tending to bunch just before sunset which may pose additional risk to vessels navigating the East Lamma Channel."
The recent unpublished report was by Yip Tsz-leung, associate director and co-founder of the CY Tung International Centre for Maritime Studies.
He said the trend for faster, bigger ferries meant that when an accident does happen, the force of the collision is stronger, causing more injuries and possibly death. He said: "There are fewer cargo ships in the harbour.
"On the other hand, we have more passenger ships which are more frequent, bigger and faster.
"More people may pass away as the impact of an accident will be very huge."
Yip said that accidents in the waters around Hong Kong - the second busiest port in terms of ship arrivals - had halved in the last 20 years ago and were on a consistent downward trend.
He said that because there were fewer accidents, people had become complacent and were less vigilant about safety measures, such as knowing where lifejackets were located.
A Marine Department spokeswoman said there was no "clear, upward trend" of more injuries or deaths in port traffic accidents. Since 2000, the average number of collisions per year was 195 and "barring a few more serious cases resulting in casualties, most of the collisions recorded were minor contacts".
The last time marine officials conducted a comprehensive study of traffic risk in Hong Kong waters was in 2004, when it commissioned a HK$2.5 million report that forecast a five per cent increase in incidents by last year.
The Marine Department said last night in a written reply: "The 1997 report was based on the planning framework at that time, including the Lantau Port, West Lamma Channel and Lamma Breakwater, which have not materialised after the report was completed.
"So it is not appropriate to comment on the information in the 1997 report which might have been overtaken by events."