Opposition parties led by the Congress in Rajya Sabha on Wednesday described the Citizenship (Amendment) Bill as unconstitutional, alleging it discriminates against refugees on the basis of religion, and cautioned the government that the proposed legislation would not stand judicial scrutiny.

Initiating the debate on the bill, Congress leader Anand Sharma attacked the BJP saying the manifesto of any political party cannot be above the Constitution of India.

The ruling BJP has claimed that it had won 'mandate' on the basis of its manifesto, which clearly talked about the amendments to the citizenship law.

The Citizenship (Amendment) Bill, 2019, which has already been approved by Lok Sabha, proposes to give citizenship to Hindus, Christians, Parsis, Jains, Budhists and Sikhs facing religion persecution in Pakistan, Bangladesh and Afghanistan.

Opposing the bill, Sharma said the proposed legislation moved by Union home minister Amit Shah is 'divisive', 'discriminatory' and against the fundamentals of the Indian Constitution.

Sharma, a former Union minister, said that though the bill was part of the 2019 manifesto of the BJP, it cannot override the principles of the Indian Constitution.

'Every political party has right to have its own manifesto. But the manifesto of any political party cannot be above the Constitution of this country,' the deputy leader of Opposition said.

Taking a dig at the home minister, Sharma said: 'You are saying this is a historic bill, but how it would be evaluated in the history, this you get to know later.'

Congress leader and former Union minister P. Chidambaram termed the bill as 'a slap on the face of Parliament'.

'Parliamentarians are being asked to do something unconstitutional and then the baby is passed on to the judiciary and in the judiciary, lawyers and judges will decide what you have done is constitutional or not. Knowing this is unconstitutional, I am afraid this government is ramming through this bill in order to advance its Hindutva agenda,' Chidambaram said.

'This is a sad day. Thankfully they are not amending the Constitution, they are only making a law, and I am absolutely confident, I am absolutely clear in my mind, this law will be struck down,' he said.

He alleged that 'a small part of the Constitution is sought to be wrecked and demolished by this insidious Bill'.

'Fortunately we have three organs of the state, the executive is complicit, the legislature is being invited to collaborate. Hopefully the judiciary will strike it down and will save India and the idea of India,' he said.

The former finance minister also sought to know why the bill excludes Sri Lankan Hindus and Bhutanese Christians.

Trinamul MP Derek O'Brien too termed the Bill unconstitutional and warned of a people's movement against the bill. He also said it would be challenged in the Supreme Court.

He said the present bill has been drawn from 'Nazi Coffee Book' and is part of BJP's 'agenda'.

Derek alleged that through the citizenship bill and the National Register of Citizens, the ruling party wants to alienate genuine Indians from their own country.

'We will not let it happen anywhere in the country,' he stressed.

Samajwadi Party MP Javed Ali Khan said through the proposed legislation, the BJP was fulfilling the dream of Muhammad Ali Jinnah, the founder of Pakistan.