Oil, copper and gold prices were also underpinned by the talk as well as by recent positive economic data from Europe and the United States, while the dollar hovered near multi-month lows against higher yielding currencies.

Markets expect the Fed to expand its current asset purchase scheme, committing to buy $45 billion of U.S. debt and extend its purchases of mortgage-backed debt, to help sustain the fragile U.S. economic recovery.

"We think that more quantitative easing is coming and this next round will be the most aggressive yet," said Ralf Preusser, head of European rates research at BofA Merrill Lynch Global Research.

European shares were on course for an eighth straight day of gain ahead of the Fed decision, which is due after markets in the region close, though the FTSEurofirst 300 index .FTEU3 was barely changed in early trading after hitting an 18-month high on Tuesday.

London's FTSE 100 .FTSE, Paris's CAC-40 .FCHI and Frankfurt's DAX .GDAXI all opened little changed from the previous day's level, while a 0.1 percent drop in U.S. stock futures hinted at a soft Wall Street open. .L.EU.N

Earlier, MSCI's broadest index of Asia-Pacific shares outside Japan .MIAPJ0000PUS gained 0.5 percent to hit a fresh 16-month peak, helping push the MSCI world equity index .MIWD00000PUS up 0.1 percent to 337.36 points.

The euro pulled further away from a two-week low of around $1.2876 seen on Friday and stood at $1.3001, hanging on to the gains made after Tuesday's surprisingly strong ZEW economic sentiment index in Germany.

The dollar stood at 80.05 against a basket of major currencies .DXY, barely changed from late U.S. levels on Tuesday, but against higher yielding units like the Australian, New Zealand and Canadian dollars, it was drifting lower..

London copper was up 0.5 percent at $8,139.75 a metric ton (1.1023 tons), near two-month highs, while spot gold inched up 0.1 percent to $1,713.15 an ounce.

Brent crude traded above $108 a barrel as the Organization of the Petroleum Exporting Countries (OPEC) prepared to meet in Vienna where it was widely expected to retain its output target of 30 million barrels per day.

Brent futures were up 33 cents at $108.33 a barrel while U.S. crude was 21 cents higher at $85.99 a barrel.

(Reporting by Richard Hubbard. Editing by Alastair Macdonald)

• A Permanent Economic Emergency