The boss of the Fragrance chain of hotels is believed to have paid A$5.5 million (S$5.46 million) for a prized island off the north-east coast of the Australian island state of Tasmania - complete with an airstrip, lighthouse, jetty and colonial-style homestead.

Mr Koh Wee Meng, 52, chief executive and founder of Fragrance Group, reportedly plans to use the 287ha island, called Waterhouse Island, as a private retreat before he develops an eco-tourism project on it.

A property title search showed Mr Koh bought the freehold island through a firm registered in Victoria, of which he is the sole shareholder.

Named after an early 19th-century British naval captain, the island is about 1km wide and 4.5km long and has a history of farming, mostly sheep. More than 106ha of the island was declared a conservation area in 2011 by the state authorities.

Covered in pristine grassland, rolling hills and a rugged coast that includes a stretch of white sandy beach, it has a permanent power supply and mobile phone reception despite its remote location. It can be accessed by boat or plane.

The island also has a three-bedroom homestead as well as a cottage guesthouse and a shed that was once used for shearing sheep. For the past 45 years, it has been owned by a family who used it for holidays.

Mr Ant Manton, a Tasmanian real estate agent who handled the deal, said the sale of Waterhouse Island had generated interest from around the world.

"We had enquiries locally as well as national and international," he said, but added he could not name the buyer or the transaction price due to a confidentiality agreement. "It is a magnificent, remote island," he told The Straits Times. "This is probably the largest freehold island off Tasmania that has transacted in at least the past decade."

Fragrance Group, which is listed on the Singapore Exchange, did not respond to queries by press time.

Mr Koh's net worth is estimated to be US$1.02 billion (S$1.4 billion) by Forbes magazine. His company has been snapping up properties in Australia in recent years. As at March 31, Fragrance Group owns seven properties located in Hobart, Melbourne and Perth.

One of these is Premier Tower, a 78-storey skyscraper in the heart of Melbourne which will have 780 apartments and a 175-room boutique hotel when it is completed. Fragrance Group has sold about 70 per cent of the apartments.

Mr Koh's brother, Aspial Corporation chief executive Koh Wee Seng, has also been active in the Australian property market.

Aspial is developing Australia 108, a 100-storey condo that will be Melbourne's tallest residential building when it is completed in 2019.

Australia is surrounded by thousands of islands, but few are open to private ownership and sales of entire individual islands are rare. Tasmania is believed to be surrounded by more than 4,000 islands and rocky outcrops but only nine are freehold.

Purchases of islands in Australia have often been considered the preserve of tycoons, celebrities, multimillionaires and lottery winners, though relatively affordable islands occasionally come up for sale.

Islands that were recently offered for sale include Elizabeth Island, a small low-lying island near Melbourne; and The Duke Group Archipelago, a set of three islands off the state of Queensland which was listed for about A$12 million.