Subba, who represents Tezpur constituency from the ruling Congress party in the Parliament is alleged to be a Nepali national, whose actual name is Moni Kumar Limbo.

The Central Bureau of Investigation (CBI), started a probe to check the veracity of his nationality in 1997.

The apex curt today said that it was "annoyed" by the affidavits filed by the CBI, in which it was not mentioned whether Subba was from India or Nepal.

"The court has clearly said that even in CBI reports it is nowhere mentioned that he is an Indian national. His names appear suddenly in the electoral rolls in 1985. There are no documents- school leaving certificate pertaining to him dated before that," A.K.Sinha, public prosecutor in the case, told reporters after the day's proceedings.

Sinha added the court said various conclusions drawn by the CBI contradicted each other.

"Even earlier the counsel appearing for the CBI said that enquiry was made and there is nothing against Subba. But that is not true. In fact, the CBI report itself says the enquiry is not conclusive, because important documents are missing, and the Government of Nepal is not cooperating... they are not sending finger prints of Moni Kumar Limbo, who is allegedly Moni Kumar Subba," said Sinha.

The Congress Party refrained from commenting on the issue, saying the matter was sub-judice. It, however, said no conclusions should be drawn till a final judgment was made.

"The date of the matter was deferred by six weeks, within which time he is given liberty to file whatever material, documents et cetra ... information that he may like to choose to file and the CBI would obviously have the right to examine him. And the matter was deferred, I wish to make it clear that no interim or final order was passed by the court," Abhishek Manu Singhvi, Congress spokesperson, told reporters at a news conference.

The controversial MP was also embroiled in a multi-crore lottery scam in 1999.