A Vajrayana centre during the 8th and 9th century AD, Udaygiri is home to remains of several stupas, one of them, the Dhyani Buddha, boasting descriptions in Vajrayana text, the official said.
"Even as a Central directive banned such activities within 5 km radius of any protected monument, there has been indiscriminate onslaught on the remains of various stupas here under the pretext of permits issued by the local administration," said an official of Archeological Survey of India (ASI).
"The contractors, in connivance with government officials, have been illegally lifting stones and morrum from the hillocks," seconded Pradip Bhuyan, vice-president of Buddhayan, an organization which works for the protection of Buddhist sites in the state.
"Each day about 50-70 trucks carry stones and morrum from the Udayagiri hill," he said, adding due to such illegal activity under the very nose of the authorities, the southern portion of the hill is now on the verge of collapse.
Buddhist sites at Sukhuapada, another prohibited area near Lalitagiri, have also been facing the onslaught of quarry workers. Likewise, Landa hillock, also under ASI protection, is being ravaged too, Bhuyan said.
The tragedy is compounded by the fact that the famous Buddhist sites at Lalitagiri, Udayagiri and Ratnagiri in the state are fit to get the status of World Heritage Sites like Sun Temple of Konark, but the chances are being hampered by the large scale quarrying near the hillocks, an ASI official said.
Several ancient Buddhist monasteries in the region are also being threatened by illegal quarrying, he added, lamenting the lacunae in preserving the natural environment of the Buddhist monasteries so that they can be awarded the status of World Heritage Sites.