The Prime Minister expressed his anguish through a tweet after a delegation of BJP lawmakers from Other Backward Classes met him in Parliament to thank him for the passage of the bill in the Lok Sabha.

According to a statement issued by the Bharatiya Janata Party, the Prime Minister said: "This bill will ensure justice to backward classes and also help in their social empowerment."

Modi said he was shocked by the attitude of the opposition parties on the bill.

"It is surprising that the bill has not been passed in the upper house. This happened after recommendations of a parliamentary committee on OBCs on the issue. Even MPs from all parties met me and urged to make the amendment in the Constitution on the matter," Modi said.

Urging the party MPs to persuade the opposition MPs on the issue, Modi said: "To stop backward classes from (getting) their rights, by doing such nagative politics, is regrettable." 

BJP General Secretary Bhupender Yadav said the Prime Minister asked party MPs to spread the message of the bill and make the backward classes aware about it.

The bill to accord constitutional status to the National Commission for Backward Classes was on Tuesday referred to a Select Committee of the Rajya Sabha after the opposition parties blocked its consideration in the house.

A motion for sending the National Commission for Backward Classes (Repeal) Bill to the Select Committee was moved by Minister for Social Justice and Empowerment Thaawarchand Gehlot and it was adopted by the upper house.

The bill was passed by the Lok Sabha on Monday and the government tried to push its consideration by the Rajya Sabha but a combined opposition resisted it.

The government on April 5 introduced separate bills to constitute a commission for the socially and educationally backward classes -- to be known as the National Commission for Backward Classes -- and to repeal the National Commission for Backward Classes Act, 1993.