Europe's major stock markets firmed at the open on Wednesday, before the conclusion of the US Federal Reserve's penultimate interest rate decision of the year.

In initial trade, London's benchmark FTSE 100 index of major blue-chip companies added 0.22 percent to 6,379.62 points.

In the eurozone, Frankfurt's DAX 30 won 0.34 percent to 10,728.16 points with Volkswagen posting better than expected results, while the Paris CAC 40 won 0.22 percent to 4,857.85 compared with Tuesday's close.

In contrast, Asian equities mostly fell on Wednesday as weak US economic data sent investors running for safe havens.

"The Federal Reserve will be making its penultimate decision of 2015, with policymakers probably more divided about when to raise rates than at any other time in the past few years," noted CMC Markets analyst Michael Hewson.

"While no change is expected today the statement will be closely scrutinised for any change of tone with respect to the timing of a rate rise this year."

On Tuesday the US Conference Board said an index of consumer confidence fell in September owing to a gloomier outlook for the economy, while the Commerce Department said durable goods orders dipped for a second straight month.

The figures come after a Labor Department report at the start of the month showed jobs growth was weaker than expected in September, increasing the chances the Fed will keep rates on hold until the new year.