Former Lok Sabha speaker PA Sangma on Sunday claimed that a demographic change was taking place in Assam and cautioned the people against the "silent invasion" in most tribal-dominated regions.

"According to the May 24, 1971 formula, Bangladesh nationals were to be identified and deported to that country. But 25 years have since been passed and Rs. 400 crore spent, only a thousand Bangladeshis were identified and only one was deported from Assam," Sangma claimed while addressing a gathering in Ranchi.

He said north-eastern states did not allow too much industrialisation because "outsiders" would come to seek jobs and then settle down, "changing the demography".

"Tribals are self-content about what they earn that is why Bangladeshis are working even for Rs. 25 on daily wages, changing the demographic structure. But the structure should be maintained by being careful and aware of the silent invasion," he said.

Sangma, who during the day visited Nagri situated on the outskirts of Ranchi, said he would study the Nagri land dispute before taking up the issue.

The villagers of Nagri are protesting against the government's proposal to set up an education hub there.