Terming the Tehelka expose of his alleged encouragement of the killings of Muslims in the post-Godhra riots as "shocking and mind-numbing", the Congress on Friday demanded that Gujarat Chief Minister Narendra Modi should step down immediately.

"Narendra Modi has lost all moral and constitutional authority to continue in office. We have said this before and will repeat it now," Congress spokesperson Jayanthi Natarajan told reporters in Delhi.

She said Modi should immediately step down from public office if the Constitution has to be upheld and if human rights are to be protected.

"The shocking and mind-numbing revelations that have come to light as a result of investigative journalism by Tehelka prove beyond a shadow of doubt what the entire country has known since 2002," Natarajan said.

"The chief minister of Gujarat has presided over and extended both tacit and overt support to mass killing and genocide and also perpetration of the worst kind of human rights violation and murder," she said.

"The response of the Bharatiya Janata Party to these serious revelations is even more shocking. There is a deafening silence from senior leaders of the BJP, who have not come forward to condemn these horrific incidents," Natarajan said.

She said the official response of the BJP through its spokesperson was "callous and irresponsible" and remarked that the BJP needs to come clean on the issue and explain its position to the nation.

Congress leader Kapil Sibal said in a statement that the sting operation was further proof that Modi and democracy were antithetical to each other.