"He has been admitted and is in a private ward at AIIMS. He will have to undergo a surgery tomorrow," a source close to the minister said.
The source added doctors of the nephrology department of the institute were attending to the minister's ailment.
Tewari, 48, has been unwell for quite some time and had undergone hospitalisation at a south Delhi hospital only a few days earlier.
The Union Minister was expected to be Congress' candidate from Ludhiana Lok Sabha constituency, from where he had won the election in 2009, but has not been fielded by his party this time.
Tewari had earlier said that he was not in the poll fray because of his health about which he is learnt to have conveyed to his party's leadership.