A purchase spree by affluent foreigners and a huge number of local rich and well connected individuals rendered the island vulnerable to further exploitation.
National Museums of Kenya director general Idle Farah said most of these foreign fat cats descended on the island, buying out ancient and historical buildings, once it was listed as a world heritage site by UNESCO in 2001.
Mr Farah added that the islanders who are the majority are living in grinding poverty and cannot resist the temptation of selling their houses to well-off foreigners who are ready to spend fortunes on the properties.
"Lamu is one of the world heritage sites in danger of losing its rich culture and traditions owing to large scale sale of old buildings by locals to wealthy foreigners," the NMK boss said.
"Once UNESCO listed the island as a world heritage site well monied foreigners including Hollywood greats are fighting for ownership of buildings here. The culture will be wiped out if the trend continues," he lamented.
He said although NMK and Lamu County Council have been sensitising the islanders on the need for them to stop selling their properties, the problem still persists.
"If foreigners take over the buildings it means the Lamu people will have to leave. A foreign culture will set in and rip apart the heritage of this historical island," Mr Farah added.
The NMK boss made the remarks at Sarova Whitesands Beach resort on the sidelines of a final directors' seminar of the Africa 2009 programme which was attended by participants from 30 Sub-Saharan Africa countries.
Mr Farah said grabbing of land by influential individuals on the island was degrading the environment through unplanned development by foreigners and rich locals.
He, however, said NMK in collaboration with Lamu County Council was educating the islanders on the need to stop the sale of their houses.
Zanzibar Stone Town Conservation and Development Authority director general Issa Makarani urged the Kenya government to formulate laws which would prevent foreigners from buying old buildings in Lamu and turning them into luxurious private homes.
Mr Makarani said in Zanzibar there was no way a property owner could demolish an old building and in its place construct posh houses since such a trend would ruin the heritage sites.
He noted that seven years ago the government banned the construction of more tourist hotels on the island to prevent the erosion of the world heritage site.
Mr Makarani said it was only the Conservation and Development Authority which has the powers of issuing licences on reconstruction of buildings, saying the law has been effective in barring foreigners from turning ancient properties into luxurious homes.
Uganda Museums and Monuments acting commissioner Rose Nkaale said her country was also grappling with the problem of purchase of old buildings by foreigners who later demolish them and build skyscrapers.
Ms Nkaale added that foreigners had purchased buildings on the Old Kampala town which is under conservation before demolishing them to put up storeyed buildings