NEW YORK - The level of U.S. commercial real estate deals seen in the boom years of 2005 through 2007 may take a generation to return, according to a report by real estate services company Jones Lang LaSalle Inc.

U.S. commercial real estate sales in the first half of 2009 totaled $16 billion, down 80 percent from the same period a year earlier and off 93 percent from the market peak of $231.4 billion in the first half of 2007, according to the firm's U.S. Mid-Year Capital Markets bulletin, released on Wednesday.

At $5.2 billion, second-quarter sales were easily the lowest on record, down from $30.7 billion in the year-earlier quarter and off 95 percent from $114.7 billion in the second quarter 2007.

From the peak of the market to the end of the second quarter 2009, U.S. office asking rents fell on average 10 to 25 percent. Office leasing is down 25 to 50 percent. Commercial real estate prices are off 30 to 55 percent, according to the report.

The credit crisis, which accelerated at the end of last year, essentially shut down mortgage lending and other loans critical for real estate sales and refinancing. Although lending to selected borrowers has resumed somewhat, the U.S. recession has pounded rents and occupancy rates.

It is unlikely that any true debt liquidity will return to the market until mid-2010 at the earliest, Kenneth Rudy, president of Jones Lang LaSalle's Capital Markets practice, said in a statement.

Meanwhile, first-year yields on the building purchases have moved up 2.5 percentage points. The yield, also called a cap rate, moves inversely to the price, and a 2.5 percent cap rate rise could knock a third off prices.

Prices for office buildings are not expected to begin to recover until at least 2012 because commercial real estate performance, which is based on job growth, lags the economy. The retail and lodging markets also will need additional time to recover as they depend on consumer spending and business travel.

Jones Lang LaSalle predicts that U.S. investors will slowly begin to return to the market by mid-2010, though a return to the boom years of 2005 through 2007 will take a generation or longer.

Instead of $231 billion a year in deals, U.S. commercial real estate sales are likely to hover around $100 million on average for the first several years of the next decade.

(Reporting by Ilaina Jonas, editing by Matthew Lewis)