Nov. 9 (Bloomberg) -- London Stock Exchange Group Plc, Europe’s oldest independent bourse, said a technical problem related to one part of its trading system affected 1 in 12 U.K. stocks and trading for those won’t resume tonight.

LSE “is continuing to investigate an issue impacting our trading and information platforms and this issue continues to impact one twelfth of London instruments,” the exchange said on its Web site. “Customers should be aware that the trading of affected stocks will not be resumed this evening. A closing auction will not take place for the affected stocks.”

The glitch comes two years after LSE was forced to extend its closing auction by an hour and a half after a technical problem affected live prices, causing the biggest disruption in seven years. That incident left some traders without prices for as much as 40 minutes and spurred gyrations in the benchmark FTSE 100 Index.

The London-based bourse, which said earlier today it’s increasing capacity fivefold for customers who want to locate their computers inside the bourse’s data centre, is confronting alternative trading systems including Bats Europe and Chi-X Europe Ltd., which trade the same stocks and offer lower fees and faster trading. In response, LSE Chief Executive Officer Xavier Rolet has been changing trading tariffs and is seeking to improve the bourse’s technology.

MillenniumIT, Turquoise

LSE is buying MillenniumIT for $30 million to gain access to the Sri Lankan technology-services company’s trading systems and may acquire Turquoise, the trading system created by its biggest customers as an alternative to stock exchanges.

“All non-executed orders for impacted securities will be deleted,” LSE said today. “Customers are advised to perform an own order book download tomorrow, which should illustrate a clear order book.”

LSE hasn’t been the only bourse facing technical glitches. ING Groep NV stock was suspended in on NYSE Euronext on Oct. 27 after a “huge concentration” of orders overwhelmed computers on the Euronext system. Trading resumed the next day.

To contact the reporter on this story: Nandini Sukumar in London at nsukumar@bloomberg.net; Alexis Xydias at axydias@bloomberg.net

Last Updated: November 9, 2009 12:31 EST