When advertising executives talk about the most promising global growth markets, the conversation usually starts with China or India and only later meanders around to Russia.

　　But moves by Rupert Murdoch, head of the News Corp. conglomerate, and Martin Sorrell, chief executive of the marketing company WPP Group, to place big bets on Russia made it a conversation starter. By some measures, Russia is, in fact, the world's fastest-growing advertising market.

　　Last month, WPP announced a link with Video International, one of the biggest advertising agencies in Russia, under which WPP businesses in that country will operate as joint ventures with Video. News Corp., meanwhile, has disclosed plans for a big expansion of its already sizable presence in the booming Russian billboard market.

　　Both companies are seeking to tap into a bigger share of the roughly $5 billion that Zenith Optimedia, a media buying firm owned by Publicis Groupe, expects advertisers to spend in Russia this year. That represents a 32 percent increase from last year.

　　But, as the shifting fortunes of Mikhail Khodorkovsky - the jailed founder of Yukos who is awaiting a verdict in his fraud and tax evasion trial - demonstrate, doing business in Russia can still be a roller-coaster ride, making some foreign investors wary about expanding their presence.

　　"It's not an easy market to operate in," Sorrell said in a recent interview. "You need a lot of local knowledge."

　　Unlike many subsidiaries of foreign advertising companies that opened up in Russia, Video International was founded locally, with support from Mikhail Lesin, a former press minister who now serves as an adviser to President Vladimir Putin.

　　But competing agencies have also managed to grow rapidly. The Moscow office of Leo Burnett, part of Publicis Groupe, has expanded to about 120 people from about 10 when it opened for business a decade ago.

　　Much else has changed in that time, noted Vladimir Novoselskiy, managing director of Leo Burnett in Russia. Last year, 61,000 brands were advertised in a country that 10 years ago had barely any. There is now more billboard advertising in Moscow alone than in all of Britain, he says.

　　"Unfortunately, we call this the jungle," he said. "You have to be really creative to stand out."

　　Indeed, Russian consumers have grown increasingly savvy and appreciate advertising that is as sophisticated, witty and subtle as the best work in the West, he said. Meanwhile, the Duma - the lower house of Parliament - has placed new restrictions on things like alcohol ads, allowing them on television only between 10 p.m. and 7 a.m., for instance.

　　Behind the seemingly rosy numbers on ad spending, some constraints also become evident. More than two-thirds of the recent increases in spending, Novoselskiy said, was caused by "media inflation" - that is, a rise in the cost of time on television or space in newspapers, rather than growth in advertising volume.

　　Television, in particular, suffers from this problem because of a limited number of channels with nationwide reach. Demand for billboards is also outstripping supply, he said.

　　While that is good news for media owners, Novoselskiy also sees an upside for advertising agencies.

　　"As the cost of media grows, the quality of what you put on the air is growing more important," he said. "There is a strong need for a better creative product."