It is too soon to determine when the U.S. recession ended, the arbiter of U.S. business cycles said on Monday.

Although most indicators have turned up, the committee decided that the determination of the trough date on the basis of current data would be premature, the National Bureau of Economic Research said in a statement.

Many indicators are quite preliminary at this time and will be revised in coming months, the group said.

The NBER said its business cycle dating committee, a group of economists that pinpoints when recessions begin and end, had met on April 8 to consider whether it had enough data to call the end of the latest slump.

The group looks at a range of indicators, not just gross domestic product, to determine when business cycles begin and end, and is well known for waiting many months before making its determinations.

During the last recession, which ended in November 2001, the NBER waited until July 2003 to make the determination, in part because unemployment continued to rise well after the business cycle had turned.

However, some committee members have said recently that they believed the recession ended last summer or fall, judging by economic growth, employment and other factors.

Many private economists think the downturn probably ended in June or perhaps a couple of months later. The economy resumed growth in the third quarter of 2009, although employment continued to contract for several more months. Payrolls have recorded only two monthly gains since the recession started -- in November 2009 and March 2010.

WHY THE DOUBT?

The NBER defines a recession as a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production, and wholesale-retail sales.

That means it does not follow rules of thumb such as two consecutive quarters of GDP to signal a recession, nor does it declare them over once GDP turns positive.

A closer look at the range of indicators the NBER watches helps explain its reticence. For instance, while real GDP has been growing since the middle of 2009, personal income flattened in February and industrial production growth has been inconsistent.

The next report on industrial output is due on Thursday, and economists are looking for a relatively robust gain of 0.7 percent, which would be far ahead of February's 0.1 percent.

The NBER said its committee reaffirmed that the recession began in December 2007.

(Reporting by Emily Kaiser; Editing by Chizu Nomiyama)