Controversial Congress parliamentarian from Assam's Tezpur constituency, Mani Kumar Subba who has been asked by the Supreme Court to respond to CBI's report that he is a Nepalese and his birth certificate is fake, is under pressure from both his own and opposition parties to resign.

Assam Education Minister and government spokesman Ripun Bora said in Guwahati on Tuesday that following the Supreme Court directive, Subba should resign from his seat and uphold the party dignity.

"The CBI is a premier investigating agency and since it has submitted to the Supreme Court that the birth certificate submitted by Subba is fake, the MP must quit," he said.

People had a suspicion about his identity and he should settle the matter first, said Bora, a legislator from Gohpur, which falls under Subba's parliamentary constituency.

Assam Pradesh Congress Committee general secretary Bhupen Bora, legislator from Bihpuria also falling under Subba's constituency, said the people of Tezpur were upset to know that their representative was not an Indian and Subba should respect their sentiments and do the needful.

The opposition Asom Gana Parishad spokesman Apurba Bhattacharjee said it was shameful that the Congress had sent a candidate to the Lok Sabha whose citizenship was in doubt and now it must maintain the minimum norm of democracy by ensuring his resignation from his parliamentary seat.

BJP's state unit spokesman Dhruba Prasad Baishya said the fact that a foreigner had contested elections on the basis of fake birth certificate and represented a constituency twice in Lok Sabha was indeed a matter of grave concern.

"The security of the nation is at stake when people with dubious antecedents successfully contest elections and become peoples' representatives," Baishya said.

The Supreme Court had on Monday directed Subba to respond to a CBI report which questioned the veracity of his birth certificate following a probe over a petition which alleged that he was a Nepali.

The Supreme Court also observed that the birth certificate produced by Subba was not genuine and the CBI report was against him.