The international cooperative project to find the best way for restoring damaged cultural relics at a UNESCO World heritage site in central China's Henan Province has been completed, a senior official with the local cultural relics administration confirmed Wednesday.

The project, targeted at Longmen Grottoes in Luoyang City, was jointly sponsored by UNESCO (United Nations Educational, Scientific and Cultural Organization) and Chinese and Japanese governments.

It took eight years to complete the 1.25 million-dollar project to help preserve the on-the-cliff Buddhists statues and carvings that survived floods, wars, theft and other natural or manmade disasters during the past millennium.

The grottoes are threatened by weathering caves, collapsing rocks and seeping groundwater, according to Chen Ailan, head of the municipal cultural relics administration of Luoyang.

Visitors to the grottoes can hear water dripping down in every cave during the rainy season that can last months.

Cracks were found in each of the 37 major grottoes in Longmen, 29 of which were inside a single grotto, according to a two-year investigation by a crew of experts from China Geology University, China Cultural Relics Research Institute and Longmen Grottoes Academy.

Thanks to the project, a database of damages to the grottoes had been set up, and an experiment to select the optimum way to pour seepage-proof mortar to fill the cracks inside the grottoes has been conducted.

On the basis of the experiment, which was done in three pilot caves, a feasible general restoration plan had been worked out, Chen told Xinhua.

Featuring outstanding Buddhist carving craftsmanship, Longmen has more than 2,300 grottoes with 110,000 Buddhist images, more than 70 dagobas and 2,800 inscribed tablets on cliffs with a length of one kilometer along the Yishui River, where Buddhism was first introduced to China during the Eastern Han Dynasty (25-220).