Lupin and Cipla, which rank among India's top five drugmakers by sales, submitted first-round offers in late April for UCB's Kremers Urban Pharmaceuticals Inc unit that could be valued at about $1 billion, Bloomberg said.
A UCB spokeswoman told Reuters that a sale process involving multiple parties was ongoing, and the company hopes to reach an agreement by the end of the year.
Cipla would not comment on "product or partner discussions" but it is "constantly in discussions with multiple parties on potential collaboration opportunities", a company spokeswoman said in a statement.
A Lupin spokesman did not immediately respond to a request for comment.
In November, UCB had agreed to sell the US generics business to private equity groups Advent International and Avista Capital Partners for about $1.53 billion, but the deal fell through in December.