The fate of at least four newly graded historic buildings is uncertain because they have fallen into the hands of companies looking for redevelopment opportunities. A new development plan has already been approved for a grade three residential block in Sai Ying Pun. And three tenement buildings in Sham Shui Po - with their status lowered from grade two to grade three - have been taken over by acquisition companies. They are just a handful of similarly affected buildings among 1,444 historic sites on a list announced last month, said experts who called for a review of the planning system and the setting up of a compensation mechanism. They said these cases showed the need to strengthen the fragile heritage conservation system. Under existing policy, only buildings declared as monuments enjoy legal protection from demolition. Graded buildings are regarded as having varying degrees of heritage value but are not protected by law. The Antiquities Authority can declare a grade one building as a provisional monument to allow negotiations with the owner. A Post investigation into ownership of graded buildings found some are exposed to the risk of demolition and could be sold for redevelopment. One example is a three-storey Chinese townhouse in Hing Hon Road, Sai Ying Pun. Described as a typical example of simplified classical architecture, it was built in 1917 and given grade three status last month. Despite its historic status, the house will be redeveloped into a residential building of 31 storeys with a clubhouse, according to a building plan approved by the Buildings Department early this year. The site was sold to acquisition company Widemax Limited in 2007. Three tenement buildings in Sham Shui Po are exposed to similar risk after their historic status was lowered from grade two to three - the lowest priority for preservation. They were among 43 buildings downgraded in the government's proposal released for consultation last month. Land Registry documents show 119 and 121 Nam Cheong Street have been taken over by Kowloon Limited, registered in the British Virgin Islands. Its manager, giving his name only as Mr Wong, declined to say whether the two buildings would be redeveloped, but he said the upper floors were now a guest house. The building next door - 123 Nam Cheong Street - was bought by another company, Fairmount Limited, in 2004. The company's secretary declined to disclose the business nature of the company. But residents and a shop have already moved out. Centaline Surveyors managing director Victor Lai Kin-fai said acquiring old buildings with a low-profile company was a common tactic of developers hoping to gain urban development rights. Developers targeted townhouses and tenement buildings because their development potential had not been fully utilised, he said. Antiquities Advisory Board member Lee Ho-yin said it was difficult for the government to protect all historic buildings unless they were protected by law. He said the government should consider incorporating graded buildings into statutory outline zoning plans to offer them legal protection, adding that Singapore, Shanghai and Macau protected heritage sites through zoning measures. Lawmaker Patrick Lau Sau-shing warned that developers might demolish historic buildings during the consultation period. 'The grading released last month is just a government proposal.' The grading could be adjusted in line with public comments after the consultation ends in July. A Buildings Department spokeswoman said it would seek advice from the Antiquities and Monuments Office if it received applications to demolish graded buildings.