Modi's sharp comments came a day after senior Congress leader P Chidambaram pitched for greater autonomy for Jammu and Kashmir yet again.
He told BJP workers here that his government would not compromise with the country's unity and integrity.
"All of a sudden, those who were in power tillyesterday have taken a U-turn. Shamelessly, they are making a statement and are lending their voice for Kashmir's azadi," Modi said.
Modi said the country has no hope or expectations from the Congress.
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Noting that Sardar Patel took important decisions for the country's unity, he said thousands of jawans have sacrificed their lives for Kashmir.
"The country's soldiers have sacrificed their lives every moment for the sake of security of the motherland and innocent citizens of Kashmir.
"I want to ask the people of Bengaluru, can the country benefit from such people who are playing politics on the sacrifice of our soldiers? They don't have any shame in saying this. The Congress party willhave to give an answer for this (Chidambaram's) statement...," he said.
But, he said, the Congress was "shamelessly using such language that is used by the separatists on Kashmir's land. (They are) using the language that is spoken by Pakistan."
Stressing that this was the land of Sardar Patel, he said, "We will not compromise with the country's unity and integrity and we will not allow it happen."
"Yes, I do," Chidambaram said when he was asked if he still thinks that Jammu and Kashmir should be given greater autonomy.
Chidambaram had in July 2016 advocated greater autonomy for J&K, saying India should restore the "grand bargain" under which Kashmir had acceded by granting a large degree of autonomy to it.
The Congress, however, has sought to distance itself from the remarks of Chidambaram on Kashmir, saying the "opinion of an individual is not necessarily the opinion of the party".
Congress chief spokesperson Randeep Singh Surjewala had said Jammu and Kashmir is an integral part of India and "will always remain so unquestionably".
At the BJP workers' meet here, Modi also said when India carried out the surgical strikes across the Line of Control (LoC) in September last year, "our soldiers hit back at our enemy. It was a moment of great pride for the wholenation, but the Congress party could not digest that also".
He said, "The heroism of our brave soldiers, India's diplomatic strength, India's courage, its restraint, the whole world saw it at Dokalam (during the standoff with China).
"However strong China may be, in the test of restraint, India has lived up. Today it is India's ability which the world is looking at with respect... The Congress people are every day spreading false information in the name of Dokalam."
Hitting out at the Congress, he said, "Those who remained in power for so many years, onthose people the country had trust in, and (they) have turned out to be such? They are of such thinking."
"People learn from defeat, they understand, they rectify their mistakes, but their arrogance is on cloud seven...They have lost track of the people's expectations. That is the reason they are using such language."
Reacting sharply to Chidambaram's remarks, the BJP yesterday said it was not surprising to see Chidambaram make such comments given his leader supported those who gave slogan of "Bharat tere tukde honge", an apparent reference to Rahul Gandhi backing those who protested the arrest of student leader Kanhaiya Kumar in the JNU row.