(Bloomberg) Shares of West Siberian Resources Ltd. rose as much as 6.7 percent to their highest level ever, after the company agreed to buy a rival Russian oil producer, an acquisition that will increase its oil production by 39 percent.

The shares, which trade in Sweden, rose as much as 0.4 krona to 6.4 kronor and traded at 6.2 kronor as of 10:44 a.m. in Stockholm, valuing the company at 4.91 billion kronor ($650 million). More than 9.1 million shares traded, double the daily average of the past three months.

West Siberian pay $140 million for ZAO Saneco, which produced an average of 5,714 barrels of crude oil a day last year, the oil producers said in a statement.

?Saneco?s success rate in exploratory drilling is 100 percent,? Maxim Barski, managing director of West Siberian, said in today?s statement. ?In the last three months, Saneco opened up two new oil fields with substantial oil flow.?

Bermuda-registered West Siberian last month pumped 14,493 barrels a day. The purchased company owns four production licenses and three exploration permits.