Shares in Essar Energy Plc ESSR.L, controlled by India's billionaire Ruia brothers, rose as much as 6 percent on Monday after it received a possible takeover offer from its largest shareholder worth about 900 million pounds ($1.51 billion).
The proposal from Essar Global Fund included a possible offer of 70 pence per share for the 22 percent stake it does not already own in Essar Energy.
Brothers Ravi and Shashi Ruia, founders of the privately owned Essar Group, whose interests span energy, telecoms, steel and shipping, are also 'beneficiaries' of Essar Global Fund.
However, minority investors such as Henderson Global Investors and Standard Life were vocal about their displeasure with the proposed offer, which they deemed to be "opportunistic".
The Indian oil and gas company's stock closed up 3.3 percent at 68.15 pence on the London Stock Exchange on Monday after hitting a high of 70.00. Shares in the FTSE 250 company have steadily declined since its London listing four years ago at 420 pence.
Essar Global had said on Friday that it could make an offer on its own or as part of a consortium at a "modest" premium to the company's Thursday share close of 60 pence on the London Stock Exchange.
Standard Life criticized Essar Global's proposal in a statement on Sunday, saying the bid would deprive small shareholders of the company's future growth value.
"I think some investors may feel that they would have rather held out. It would be nicer to see the parents maybe give the chance of hoping for an eventual stronger recovery in the share price," Adam Forsyth, analyst at Arden Partners, told Reuters.
Essar Energy, which owns a series of power and oil assets in India, also operates UK's second biggest oil refinery - Stanlow in northwest England.
The London-listed company said the proposal would be considered by an independent committee of members, thus avoiding any conflict of interest.
It declined to comment further on Monday. A spokesman for Capital World Investors - Essar's second-largest shareholder, also declined to comment.
Essar Global has also made a possible offer to buy Essar Energy's 4.25 percent convertible bonds due 2016 for 80 pence per share.
Essar Global's latest move is a U-turn from its earlier plan to sell shares to dilute its 78.02 percent stake in Essar Energy so the company could meet UK listing requirements, which mandate that at least 25 percent of a company's stock be available for trading.
($1 = 0.5977 British pounds)
(Editing by Jane Merriman and Jason Neely)