Jan. 23 (Bloomberg) -- Grupa Lotos SA, Poland’s second- largest oil refiner, jumped to a six-week high after a strengthening zloty helped lower the company’s foreign- denominated debt.

Lotos shares climbed 4.3 percent to 25.35 zloty at 5:13 p.m., the highest since Dec. 8 on an intraday basis, valuing the company at 3 billion zloty ($911 million). The Polish currency rose 0.8 percent against the euro to 4.2805, its strongest in more than three months, after the country’s government bonds extended last week’s rally.

“For months Lotos underperformed due to the weak zloty because investors feared the company will pay significantly more to manage its loans in currencies other than the zloty,” Tomasz Kasowicz, an analyst at Warsaw-based Erste Group Bank AG, said by phone today.

Lotos had a $1.5 billion loan on its books at the end of June 2011, according to the company’s results for the first half of 2011. Its total net debt as of June last year was 6.8 billion zloty.

--Editor: Ash Kumar

To contact the reporter on this story: Piotr Bujnicki in Warsaw pbujnicki@bloomberg.net

To contact the editor responsible for this story: Gavin Serkin at gserkin@bloomberg.net