Sorrell was bullish on Russia at the beginning of the year, telling CNBC in January that it had a very healthy future with the Winter Olympics in Sochi and the World Cup in 2018 ahead. He added that his company was making significant investments in Russia and was looking to invest more in the country. Around 3 percent of the company's revenues come from Russia, according to Sorrell, who decided to issue the warning despite the region delivering strong results for the first six months of the year.
WPP, the world's biggest advertising firm by revenue, reported first-half sales of £5.469 billion ($9.07 billion) on Tuesday morning, an increase of 2.7 percent in sterling from the same period last year. Pretax profit came in at £532 million for the first half.
Read MoreI'm very bullish on Russia: WPP CEO
Sorrell added that the U.K. market was also performing strongly despite currency headwinds and he also saw promising growth in central eastern markets like Poland and the Czech Republic.
Shares of the company were trading higher by 2 percent at the session open on Tuesday with analysts at Citi describing the results as "decent" and reiterated its "neutral" position on the stock.
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