The world economy will be "filled with uncertainties" in 2014, with unpredictable U.S. monetary policy and volatile growth in Europe and Japan, China's vice finance minister said on Saturday.

At the China Development Forum 2014 in Beijing, Zhu Guangyao highlighted uncertainties arising from U.S. monetary policy, pointing to decisions taken by the Federal Reserve earlier in the week, when Federal Reserve Chair Janet Yellen indicated that the Fed will probably end its quantitive easing (QE) bond-buying program this fall, and may raise interest rates around six months later.

"We believe the QE exit will be completed at the Fed meeting this coming October," said Zhu.

If interest rates do rise six months after the QE exit, the effect on the U.S. economy and the rest of the world could be substantial, raising confidence in a consolidated U.S. recovery, he said.

Despite "obvious signs" of a European recovery and major progress in integration of financial regulations, the vice minister still regards European economic conditions as "very challenging".

"We are watching ongoing European structural reforms closely along with high unemployment rates in some countries."

In Japan, consumer taxes will rise from 5 percent to 8 percent in early April, and the government plans to invest five trillion yen (around 50 billion U.S. dollars) in economic stimuli.

Zhu was not so upbeat about the situation in Japan, saying that it will be "a challenge" to carry out the stimulus. Japan does not have a good record on previous, similar programs.

Zhu also pointed to risks associated with new geopolitical uncertainty, especially in Ukraine.