Investigators on Monday raided the offices of multibillionaire Rupert Murdoch's Russian advertising firm, News Outdoor, the company said.

The search comes less than a week after another high-profile company raid in Moscow, on the offices of mobile phone retailer Yevroset.

Officers from the Investigative Committee, a semiautonomous body under the auspices of the Prosecutor General's Office, also raided the offices of the city government's advertising, information and design committee, a source close to the company said.

The raids come as already jittery foreign investors have withdrawn billions of dollars from the country in recent weeks over worries of government interference in business. Russian stock markets have slumped over the summer on falling commodity prices and after Western sentiment on Russia was shaken by last month's conflict in Georgia.

The Basmanny District Court on Aug. 29 ordered the News Outdoor search under an investigation into negligence charges against Alexander Minchuk, the committee's first deputy chairman, the source said.

A News Outdoor spokeswoman said no charges had been brought against the advertising company. "We have been cleared of all previous charges, winning an appeal in court last month," the spokeswoman said, requesting that her name not be used, citing the sensitivity of the situation.

News Outdoor was in June accused of illegally receiving discounts on billboard advertising across the city from 2002 to 2007. The city government's budget loss was estimated at 242.8 million rubles ($9.5 million), Kommersant reported.

It was not immediately clear whether Monday's searches were related to the case against the company.

Investigative Committee spokesman Vladimir Markin declined to comment Monday. Calls to the city's advertising committee went unanswered.

In July 2007, Murdoch's News Corp. said it was looking to sell News Outdoor, the biggest outdoor advertiser in Russia with 34,000 billboards in 86 cities across the country.

Analysts said at the time that News Outdoor would be an interesting acquisition for state-controlled Gazprom-Media and Prof-Media, billionaire Vladimir Potanin's media holding.

In February 2008, News Outdoor said Interior Ministry officials inspected its office for reasons "connected with the activities of a third party."

Late on Monday afternoon, a reporter saw no police vehicles near the committee's headquarters or the News Outdoor office, and a News Outdoor employee referred him to the company's press office.

"The have been no searches today," a security guard at the entrance to the company's office said.

Ezekiel Pfeifer contributed to this report.