Blaming the Congress government in Assam for the continuing infiltration, Shah said the BJP was determined not to let the illegals infringe upon the rights of people in Assam and the Bodoland region.
Shah said this while addressing a public rally organised by the Bodoland Peoples Front (BPF) to mark Bodoland Day.
"Illegal infiltration started in Assam after the Congress resorted to vote bank politics," Shah said.
"The infiltrators from Bangladesh have spread across the state. They have infringed upon the rights of local youths, be they from tea gardens or Hindi-speaking community or Bodoland.
"If a BJP-BPF government comes to power in Assam, we are going to ensure that there is no infiltration in Assam," Shah said.
The BJP president termed the alliance between his party and the BPF a historic one and said it will go a long way in ensuring development in the state, and the Bodo areas in particular.
"We have decided to contest the Assam elections together with the BPF. This is not a political decision but one for the development of Bodoland. This is going to be historic for Assam."
Shah referred to the 1962 war with China, and said then prime minister Jawaharlal Nehru had bid goodbye to the people of Assam and the northeast then.
"It is because of the brave soldiers of India that Assam is today a part of India," he said.
Shah hit out at Chief Minister Tarun Gogoi.
He said Assam had been left behind on the development front the past 15 years when the Congress was in power.
"For 15 years there has only been corruption in Assam... Women are not safe in the state. And where women are not safe, the state can't progress.
"One crore people live below the poverty line in Assam. Thirty-six percent have no access to electricity. The number of unemployed stands at 23 lakh now," said Shah.