By DEBJIT CHAKRABORTY

Essar Oil, India’s second-biggest non-state oil refiner, jumped to the highest level in more than four years in Mumbai following reports OAO Rosneft may acquire a 50% stake.

The shares climbed 4.7% to 146.25 rupees, the highest since November 2010. The stock surged 42% last week, the most since the period ended April 2009.

The founders of Essar Oil are in discussions to sell up to 50% in the 400,000-bpd refinery in the western state of Gujarat, BTVI reported Monday, citing people it didn’t identify.

Billionaire brothers Shashikant and Ravikant Ruia are set to sell 49% in Essar Oil to state-run Rosneft, which pumps about 40% of Russia’s oil, for about 105 billion rupees ($1.64 billion), Business Standard newspaper reported Monday, citing a banker it didn’t identify. The deal may be announced as early as Tuesday, the newspaper reported.

“It is not our policy to comment on market speculations,” Essar Oil said in an e-mailed statement.

In December, Essar Oil signed key terms with Rosneft for buying 10 million metric tons of crude oil annually for 10 years starting as early as this year.