Indonesian shares hit a record closing high on Wednesday, with most markets in the region rising ahead of a likely rate increase by the U.S. Federal Reserve, with investors awaiting more clarity on its future stance.

Indonesia surged 1.5 percent, buoyed by financials, while Vietnam hit a nine-year closing high.

Economists polled by Reuters overwhelmingly see the Fed raising its benchmark rate to a target range of 1.00 percent to 1.25 percent, though expectations for further rate raises are fading.

The Fed is scheduled to announce its monetary policy decision at 1800 GMT.

"In the light of weak economic data released by the U.S. recently, we are really expecting they won't raise rate anymore this quarter," said Mikey Macanaig, an analyst with Sunsecurities Inc.

"However, we are still very cautious; we don't want any surprises."

In Indonesia, the top gainer in the region, Astra Internation Tbk PT climbed 4 percent and Bank Rakyat Indonesia (Persero) Tbk Pt rose 2.6 percent.

Among gainers in Vietnam, heavyweights Saigon Beer Alcohol Beverage Corp and Petrovietnam Gas Joint Stock Corp gained 2.6 percent and 2.3 percent, respectively.

Philippine shares rose 0.6 percent after the previous day's decline of 0.9 percent.   

Singapore shares edged down 0.1 percent, with the financial sector accounting for nearly half the losses.

The index was dragged down by DBS Group Holdings and UOL Group Ltd, which fell 0.9 percent and 2.3 percent, respectively.