BEIJING — Last year was tough for Asian economies but easy for the region’s central bankers. All they had to do was flood their banking systems with cheap cash and sit tight. But in 2010, they are going to have to earn their money.

Worries about economic growth have quickly given way to concerns about inflation, and investors seem split about the capacity of central banks to rise to the challenge.

As global jitters over China’s initial tightening of monetary policy demonstrate, some fear the response will be too harsh.

But other investors fret that some central banks, for instance in India and South Korea, are already falling behind the policy curve and will upset financial markets when they are finally required to squeeze inflation out of the system. For when it comes to monetary policy, a stitch in time often really does save nine.

Robert Subbaraman, the chief Asia economist at Nomura in Hong Kong, said the biggest risk facing Asia was that of an unexpected increase in commodity prices driving up inflation.

Part of the problem is that policy makers, still concerned about a possible economic double-dip in the West, are wary of withdrawing fiscal stimulus efforts and do not want their currencies to rise too fast.

And because the U.S. Federal Reserve is unlikely to raise its interest rates until the second half of this year, Asian central banks will probably keep their rates too low for too long for fear of attracting speculative money.

As a result, Nomura expects inflation-adjusted borrowing costs in 8 of the 12 countries it tracks to be negative by June — a recipe for bubbly domestic demand and asset prices.

“When we look at the region now collectively, monetary and fiscal policies have never been so loose,” Mr. Subbaraman said.

J.P. Morgan analysts say they expect interest rates to rise in some countries by early spring, but at a tepid pace relative to the Asian economic backdrop.

The bank’s economists expect the average interest rate in emerging Asia will remain three percentage points below the level implied by a widely followed rule of thumb devised by a U.S. economist, John Taylor.

Central banks, a number of them under political pressure to keep borrowing costs low, have contented themselves so far with measures to mop up some of the surplus cash they injected into their economies. “Normalization” of superloose policy, not tightening, is the ugly buzzword.

For instance, last month, India and China increased the proportion of deposits that banks must keep with the central bank, while the Philippines raised a rate on a short-term lending facility. None of the three increased their benchmark interest rates.

Given that the Reserve Bank of India on Friday issued a sharp warning on inflation at the same time as it tightened required reserves, a half-point increase in interest rates is likely to follow next month, said Prakriti Sofat and Rahul Bajoria of Barclays Capital.

“However, based on our meetings with a number of Asian central banks, the clear theme is that policy makers remain cautious, and the risks are that rate hikes may be delayed,” they wrote in a report.

The case for pre-emptive action is based not only on the rapid economic recovery in Asia, which is absorbing spare capacity and excess labor needed to keep a lid on prices, but also, some economists say, because a repeat of the 2007-8 increase in global food prices is taking shape.

Western central banks play down passing increases in the cost of food because it typically accounts for 10 percent to 15 percent of their consumer price indexes. But in Asia, excluding Japan, food makes up 30 percent to 35 percent of national consumer price indexes, so a jump in food prices can quickly increase overall inflation and harden expectations of a price spike.

Glenn Maguire, the chief Asia economist at Société Générale in Hong Kong, is among the worriers. He said the upswing in food commodity prices since 2004 had been rivaled only twice in the past century — in the 1930s during the recovery from the Great Depression and during the commodity boom of the 1970s.

He postulates that China could be having a profound effect on food inflation as strong income growth, rapid urbanization and Westernization of the local diet increases demand.

“The speed at which inflation is turning in Asia argues for a much more prudent stance on policy, and there are few Asian economies that should be exempt from tightening over the course of 2010,” Mr. Maguire said.

A more optimistic view comes from Silvia Liu and T.J. Bond, economists at Bank of America Merrill Lynch in Hong Kong. Leaving aside China and India, the two countries with populations of over a billion people, the economists said year-on-year food inflation had moderated in Asia to 1.3 percent in the fourth quarter of 2009 from 4.8 percent in the second quarter.

The memory of 2008, when inflation peaked in midyear at 8.5 percent, up 5.6 percentage points from the year before, remains vivid, the economists wrote in a weekly report. But they think a better comparison is with 2004, when inflation crested at 4.2 percent, up 2.6 points from the year before. They expect Asian inflation to accelerate to 3.5 percent in 2010 from 0.7 percent in 2009.

But they acknowledged that conditions could change.

“In particular, if China maintains a rigid FX regime, the entire region may find it difficult to tighten monetary policy, given the low levels of U.S. rates,” they said, referring to foreign exchange policies. “As a result, asset prices, money and credit growth could all rise, raising inflation risks in 2011. This is the key risk we will monitor over the course of the year.”