* Weak euro zone, Chinese data hits stock markets
* Euro falls vs dollar after PMI data; Swiss franc, yen gain
* Ukraine clashes hit emerging market stocks
By Francesco Canepa and Nigel Stephenson
LONDON, Feb 20 (Reuters) - Shares fell and safe-haven currencies rose on Thursday after downbeat surveys of economic activity in China and parts of Europe raised concerns about the withdrawal of monetary stimulus.
A contraction in Chinese manufacturing set the gloomy tone which was reinforced by data showing an unexpected stall in activity in parts of the euro zone.
"The macro data is starting to be not as good as before and some red lights are appearing in our model," Johann Nouveau, partner at Seven Capital Management, a hedge fund which uses mathematical models to gauge economic data and market momentum.
"We're still long stock markets but we're decreasing our exposure as the probability of a sharp drop is increasing."
Escalating conflict in the Ukrainian capital, Kiev, hampered developing country stocks and MSCI's emerging market index fell 1.1 percent.
Its world equity index, which tracks shares in 45 countries, was down 0.5 percent at a six-day low, having hit its highest in almost a month on Wednesday. U.S. futures were pointing to a lower start on Wall Street, with March contracts on the S&P 500 index down 0.3 percent.
In Europe, the benchmark FTSEurofirst 300 index lost 0.7 percent, with mixed PMI data from Germany, the euro zone's powerhouse, barely lifting the mood.
Markit's Composite Purchasing Managers' Index for the euro zone dipped in February, although it held just below January's 31-month high. The service sector in France shrank at its fastest pace in nine months.
"The outcome was much weaker than expected and it clearly shows how business sentiment is failing to gain momentum as headwinds to growth are still well alive," Annalisa Piazza, market economist at Newedge Strategy, said of the French data.
Earlier, Asian stocks tumbled after the preliminary China Purchasing Managers' Index from HSBC/Markit for February came in at a seven-month low, falling deeper into contraction.
"You have to expect Beijing to act if the economy slows down more from here, because they cannot proceed with their reform agenda without maintaining a certain level of growth," said Linus Yip, a Hong Kong-based strategist at First Shanghai Securities.
The data from the world's second largest oil consumer dragged Brent crude below $110 a barrel.
SAFE HAVENS & STIMULUS
The Swiss franc, which is backed by a stable economy and tends to do well at time of market jitters, rose 0.2 percent against the U.S. dollar, and the yen - another safe-haven currency - also gained.
The dollar, however, was still firm against other major currencies even after three Federal Reserve officials said on Wednesday that the U.S. economy was gaining traction despite a recent slowdown caused by bad weather, allowing the central bank to stick to its plan to wind down bond-buying this year.
The dollar index, which measures the greenback against a basket of currencies, was 0.2 percent higher at 80.28.