European markets fell Wednesday as investors remained watchful ahead of the U.S. Federal Reserve's announcement of the monetary policy decision.

The German DAX 30 index fell 0.37 percent or 23.43 points to 6339.93. Shares of Volkswagen AG fell 1.07 percent.

The French CAC 40 index fell 0.29 percent or 8.90 points to 310902. Shares of Schneider Electric SA declined 1.70 percent and shares of Danone SA fell 1.16 percent.

London's FTSE 100 index declined 0.23 percent or 12.76 points to 5573.55. Shares of Aggreko PLC fell 1.92 percent and shares of Experian PLC declined 2.08 percent.

Spain's IBEX 35 rose 0.29 percent or 19.20 points to 6713.10. Shares of Ferrovial SA rose 2.11 percent and shares of Bankinter SA advanced 2 percent.

Investors are waiting for the Federal Open Market Committee's (FOMC) statement on the monetary policy. The FOMC is expected to announce stimulus measures to rejuvenate the faltering U.S. economy.

Meanwhile, German ZEW index plunged in June to -16.9 from 10.8 in May providing further support for the view that the intensifying debt crisis in the euro zone is starting to hit Germany pretty hard. This adds to investor worries that the rapidly deteriorating situation in Spain and Italy will have a serious adverse effect on sentiment in Germany and the euro zone as a whole.

The index could easily reverse at least some of this month's fall in July, particularly if euro zone policymakers were to announce decisive measures to deal with the debt crisis at the European Council meeting later this month, Ben May, an economist at Capital Economics, said.

There is still hope that the European Central Bank (ECB) might step in to keep the Spanish borrowing costs down either by reviving its own sovereign debt purchases or by providing Spanish banks with the money to buy government bonds.