RusPetro PLC (RPO.LN), a U.K. oil and gas company focused on drilling in Siberia, Russia, Wednesday raised approximately GBP163 million through a conditional initial public offering on the London Stock Exchange.

The IPO, the first significant London listing for 2012, values Ruspetro overall at approximately GBP440 million. RusPetro Thursday said in a statement it had placed 121,542,000 new ordinary shares, representing around 59% of the company's shares, at 134 pence per share. The price is towards the bottom end of an informal range in a bookbuilding exercise launched on Tuesday, according to research from FoxDavies.

The post-offer free float is expected to be 40%. By 0930 GMT shares were trading down by over 5% at 127 pence.

"I am extremely proud that RusPetro has completed a premium listing on the London Stock Exchange at this time," Don Wolcott, RusPetro's chief executive, said in a statement. "At a time when very few IPOs have been completed, our successful listing shows that investor demand is still there for high-quality stories such as our own."

RusPetro plans to spend the bulk of the IPO proceeds on well drilling and infrastructure development in Siberia, and the remainder on paying down debt, it said in the press release.

According to a report by Interfax, the conditional IPO saw the bulk of the shares placed with around 10 investors, and the free float being shared between three funds, leading to low liquidity in the stock. A spokesman for the company declined to comment.

RusPetro plans an unconditional listing on Jan. 24, it said in the prospectus.

RusPetro's development plans include over 100 wells by 2014 and building a new 27-kilometer pipeline to the Transneft pipeline.

The company, backed among others by Altera Capital, the investment fund whose managing partner Kirill Androsov is a former deputy chief of staff to Russia's prime minister Vladimir Putin, is the latest in a line of Russian companies which have recently floated in London. Recent London-based IPOs of Russian companies include precious metals miner Polymetal International PLC (PMTL.LN) and steel maker Evraz Group S.A.(EVRZ.LN).

Bank of America Merrill Lynch acted as global coordinator and sponsor, and Bank of America Merrill Lynch, Mirabaud Securities LLP and Renaissance Securities acted as joint bookrunners.

-By Jessica Hodgson, Dow Jones Newswires; +44 7561 424788; jessica.hodgson@dowjones.com