Ophir, an upstream oil and gas exploration and production company focused on Asia and Africa, has a market capitalisation of 252.5 million pounds, according to Refinitiv data.

The company's shares closed up 7.5 percent at 35.7 pence on Monday.

Under UK takeover rules, PT Medco Energi Global has until Jan. 28 to make a firm offer or walk away, Ophir said.

(Reporting by Justin George Varghese in Bengaluru; Editing by Shailesh Kuber)