WASHINGTON, April 12-- Although most barometers show improvements in the U.S. economy, it remains "premature" to declare when this round of recession ended, according to an authorized U.S. academic organization.

The National Bureau of Economic Research (NBER), the most recognized academic organization to assess the nation's economic cycle, said Monday that it is still not ready to pinpoint the end of a recession based on economic data seen so far.

The Cambridge, Mass. based economists group met on April 8 and reviewed the country's macro economic data.

They decided that many of the key economic indicators are "quite preliminary at this time and will be revised in coming months," NBER said.

As the economy returned to growth since the third quarter of 2009, many private economists believed the recession ended in June or July last year.

However, NBER believes that it would take more time to make the declaration since the government has yet to make more changes over its estimates of economic indicators.

The NBER's assessment of economic cycle usually lags. It announced in December 2008 that the recession had actually started one year earlier -- in December 2007.

For the U.S. government and economic historians, the NBER's assessment of recession is valuable because it is often the final say among economists.