This has already been done with a site at Sai Wan, surrounded by Sai Kung East Country Park, where the owner had begun excavations for a private retreat.

The sites are among 77 nestled in or next to country parks that were not originally included in the parks because they were owned by villagers or farmers. Many of these have since abandoned them, leaving the way open for private companies to buy in. While most of the companies that have done so are not well-known developers, at least one owns multiple sites.

This has emerged from checks of records by the South China Morning Post after the government released details of the 77 sites, of which only 24 have some form of zoning.

Conservancy Association campaign manager Peter Li Siu-man said the government should now consider putting all the development-prone enclaves under protection. 'Let's put all these sites under the protection of a statutory zoning plan simultaneously,' he said.

Planning officials have said a lack of resources might be a problem, but Li said it was not impossible for officials to overcome such difficulties.

'The Planning Department once issued 30 development permission area plans in a single year during the 1990s and found no problems coping with the workload at all,' he said.

The 53 sites without protection, at least 10 of which are partially owned by private companies, cover 1,300 hectares. Some are coming under increasing threat because they are now more accessible, while their proximity to country parks adds to their development value.

A check of WWF Hong Kong's list of sites damaged in the past shows at least six of the enclaves - at least three of which are partly owned by companies - have a record of damage.

Two of the most serious instances of damage are the clearing of vegetation at Ma Shi Chau last year and So Lo Pun in 2008. There were plans for a columbarium at the former and to restore a deserted village on the latter.

Checks of ownership records of key country park enclaves in Sai Kung and Plover Cove found at least 10 private companies own or part-own 10 unprotected enclaves and six other enclaves with minimum zoning protection.

Master Mind Development holds about 200 plots at Pak Lap, which is encircled by Sai Kung East Country Park. Its sister company, Master Choice Development, is also a major owner of Ham Tin in Tai Long Wan.

In 1999, both companies entered into a mortgage agreement with a local bank and later a second mortgage agreement, involving a total loan plus accrued interest of more than HK$300 million with Yu Tai Hing Company, a private property developer with extensive investment in urban redevelopment projects.

Another Master Mind affiliate is Master Trend Development, which also holds land in Lo Lau Uk, Tai Po, on a site where vegetation was removed and a natural stream blocked by a concrete bridge for an unapproved small-house project in 2008.

These firms are owned by Dorothy Wong Sung-king and Cheung Sung-lam, who were also once directors of now-defunct Wu Kau Tang Conservation Management, which aimed to turn the priority ecological site into an experimental herb farm and a village for the retired.

A conservationist, who does not want to be named, described Wong as an 'active agent' in New Territories development. 'She once represented villagers in a public hearing of the Town Planning Board on an objection to the draft zoning plan covering Ham Tin,' he said.

Wong did not return a call from the South China Morning Post about Pak Lap, which also has a history of building through illegal access.

Another characteristic of these ownerships is their links with the rural leadership or local politicians. One of the landowners at Lai Chi Chong is Maxland (Asia), a director of which is Heung Yee Kuk councillor Leung Wo-ping.

In a telephone interview, Leung said there was no imminent plan to develop the site as land acquisition had just started and was continuing.

'We are building up the land bank for development at an appropriate time. The site can be used to build small houses. But whether such a plan can be realised will depend on the market situation,' he said.

The remoteness of the site made it uniquely attractive, Leung said. It could only be reached by ferry and if there was a housing development, it would be of high quality.

He said media reports had created a negative public perception that could frighten off investors.

'We have not even started building anything but people are saying it is bad for the environment,' he said. 'This will affect the mood of investors and those who wanted to sell the land might now have second thoughts.'

Sai Kung district councillor Lau King-for owns part of a To Kwa Peng site, where up to 80 small houses will be built, through his private company Billion Cheer Development. Tai Po district councillor Lo Sam-shing owned a stake in the Ma Shi Chau site before selling it.

Blue-chip property developers can be found in Tai Ho and Sham Chung, which are among 12 priority sites of conservation importance listed by the government. The former is owned by Swire Properties, the latter by Sun Hung Kai Properties. Another company, Trueprofit, is holding at least 40 plots in Yung Shue O.

Other developers with enclaves include Sha Lo Tung Development Company, which is working on a plan with Green Power to turn its site into a columbarium and nature retreat.

Grandbo Development also holds dozens of plots in Hoi Ha, adjoining a popular marine park known for its coral. A low-rise villa development plan from unknown sources has been circulating among environmentalists, but they are not sure if it is Grandbo's project. The company has a registered address at the Kowloon Regal Hotel, which is currently occupied by a nightclub known as Club Uno.