The Federal Reserve will need to act on interest rates, representatives from two prominent fund managers said, but they differed on the tempo.
Martin Gilbert, chief executive of Aberdeen Asset Management, said, "The Fed do have to get on with it, because they're in a difficult position."
The Federal Open Market Committee (FOMC) was set for a two-day policy meeting on Tuesday and Wednesday. But while the Fed has indicated the meeting was "live," or that action was on the table, markets haven't been pricing in much chance of a hike.
According to the CME Group's FedWatch tool, market expectations for a September rate hike were a modest 15 percent, despite data showing U.S. consumer prices increased more than expected in August, pointing to a steady build-up of inflation that could allow the Fed to raise interest rates this year.
There were reasons to be concerned if the Fed didn't act, Gilbert told CNBC at the Singapore Summit on Saturday.
"If they don't do it, people will think that they know something that we don't, and we'll see a bit of panic at that stage," Gilbert said. "I think if they do modest rise this year, that's expected. I think it's in the price and it will be well received."
But he added that he wouldn't expect an additional rate hike from the Fed until next year, and that he expected interest rates globally would remain lower for longer.
Aberdeen Asset Management had total group funds of about $402.9 billion under management as of the end of June.
But another major fund manager, Manulife Asset Management, was expecting the Fed to remain more tentative.
Geoff Lewis, global market strategist for the fund manager, told CNBC's "Squawk Box" on Monday that it would be a mistake for the Fed to hike now.
"I think they might change their language a little bit to leave things more open for a December hike because they do need to make progress," he said. "But I think it would be wrong to shock the markets at this point. It would a surprise given that the U.S. data has been weaker than expected over the last three to four weeks."
He expected the Fed may tweak its statement on Wednesday to language indicating risks were more evenly balanced, compared with the previous statement which indicated risks were tilted to the downside.
Manulife Asset Management had around $334 billion in assets under management.
—Fred Imbert contributed to this article.
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—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1