MUMBAI - British drug firm GlaxoSmithKline Plc is in talks to buy a 51 percent stake in India's unlisted Shantha Biotech after prospective bidder Sanofi Aventis dropped out, the Economic Times said on Friday.

Glaxo is negotiating with France's Merieux Alliance, which had bought a 60 percent holding in the Indian biotechnology firm in 2006 and later raised it to 80 percent, the newspaper said.

Only a few matters relating to the valuation need to be finalized, it said, citing an unnamed senior industry executive.

Glaxo is interested in Shantha Biotech to enhance its vaccine business, it said.

(Reporting by Janaki Krishnan; Editing by Ranjit Gangadharan)