Diageo Plc will launch a mandatory share tender offer to buy up to 26 per cent additional stake in India's United Spirits Ltd from public shareholders on January 7, the manager to the offer said in a notice to the Bombay Stock Exchange.

Earlier this month, Diageo agreed to buy a majority stake in United Spirits, controlled by Indian businessman Vijay Mallya, for $2.1 billion, fuelling a push by the world's biggest spirits group into fast-growing markets.

The tender offer, which is part of the two-tranche deal that will give Diageo a 53.4 per cent stake in India's largest spirits company, will close on January 18, JM Financial said in a notice to the exchange on Tuesday.

Shares in United Spirits ended up 0.6 per cent at Rs 1,762, higher than Diageo's offer of Rs 1,440 a share to minority shareholders. The sharp jump in the stock has clouded the outcome of the tendering process, analysts said.

United Spirits shares have risen more than 30 per cent since the announcement of the deal on November 9.