STOCKHOLM (Bloomberg) — Bermuda-based West Siberian Resources Ltd., whose Russian oil output climbed to a record last quarter, gained the most in two years in Stockholm trading after Renaissance Capital raised its price estimate for the stock, citing planned tax cuts.

West Siberian advanced 0.75 krona, or 14 percent, to close at 6.2 kronor, the biggest one-day increase since May 26, 2006. The stock extended its rally this year to 46 percent, valuing the company at 18.4 billion kronor ($3.07 billion).

Renaissance, based in Moscow, raised its price estimate for West Siberian to 15.9 kronor from 10.6 kronor and reiterated its "buy" rating on the stock. The bank expects the company to gain from the Russian government's planned tax cuts for oil producers, designed to spur exploration and reverse stagnating output.

"West Siberian Resources is the main beneficiary of the proposed tax breaks, through its significant exposure to the Timan-Pechora region," Renaissance said yesterday in an e-mailed report.

The government approved changes to a bill on taxes this week, granting tax holidays of seven to 10 years for projects in the remote Timan-Pechora and Yamal Peninsula regions. West Siberian boosted its Russian oil output 40 percent to 3.16 million barrels in the first quarter.

"We are currently operating in an environment with record high crude and products prices, while taxation appears to be easing," chief executive officer Maxim Barski said this month.