The World Trade Organization has cut its forecast for global trade growth this year and cautioned about the impact stemming from big exchange rate movements and geopolitical tensions.

The Geneva-based body forecast Tuesday that the volume of world merchandise trade will expand by 3.3 percent this year, down from its forecast last September of 4 percent. In 2016, the WTO is forecasting 4 percent growth.

The WTO also said that trade growth last year was only 2.8 percent, below its projection of 3.1 percent. It blamed sluggish economic growth in emerging economies, the uneven recoveries taking place in the developed world as well as geopolitical tensions for the shortfall.

It also said currency fluctuations have further complicated the global trade picture.

In recent months, the dollar has been in the ascendant as the Federal Reserve inches toward its first rate hike in years, while other developed world currencies such as the euro and the yen have been in retreat as their central banks try to stimulate their economies with cheap and easy money.

Many other currencies have also suffered big losses over the past few months as a result of the sharp fall in oil prices. The Russian ruble is perhaps the most notable faller on that front.

The WTO said it's unclear whether falling oil prices will be trade-positive or not.

Overall for this year, the WTO is forecasting a 5 percent increase in Asian exports, in line with last year's performance.

Meanwhile, it expects North American exports to grow by 4.5 percent, up from last year's 4.3 percent and European export growth to rise to 3 percent from 1.9 percent.

Exports from South and Central America should edge up 0.2 percent after falling 2.5 percent last year, it added.