The four properties are listed as World Heritage sites, but are said to be under stress from urban construction, poor governance and, or nature.

Under the new monitoring mechanism established by the World Heritage Committee in 2007, regular missions will be dispatched to sites to examine developments, and report back to the committee.

Bordeaux’s Port of the Moon in France entered the World Heritage List in 2007, but the committee said on Thursday it is worried about the visual impact of new river crossings and the destruction in late 2007 of the Pertuis Bridge.

In Timbuktu, Mali, construction near three mosques, notably that of the Ahmed Baba Cultural Centre, threatens to place the site back on UNESCO’s "in danger" list only three years after being removed from the list, the committee said.

Meanwhile in Peru, there are "urgent problems" with deforestation, the risk of landslides, uncontrolled urban development affecting the Historic Sanctuary of Machu Picchu, it said.

And the Crossroads of Cultures in Samarkand, Uzbekistan is being threatened by new roads and buildings which affect the integrity of its traditional urban fabric, in the absence of an adequate regulatory framework.

"Reinforced monitoring" continues to be applied for seven other sites deemed at risk in 2007. All seven are on UNESCO’s list of world heritage in danger, which includes a total of 30 sites.