U.S. mortgage rates fell in the latest week, trekking closer to a record low set last month.

Interest rates on U.S. 30-year fixed-rate mortgages fell to 4.82 percent for the week ending May 21, down from the previous week's 4.86 percent, according to a survey released on Thursday by home funding company Freddie Mac.

Three weeks earlier, the 30-year fixed-rate mortgage equaled the record low of 4.78 percent set in the week ending April 2, which was the lowest since Freddie Mac started the Primary Mortgage Market Survey in 1971.

Long-term fixed-rate mortgage rates have remained below 5.0 percent for the past 10 weeks as the U.S. Treasury and Federal Reserve act to keep interest rates low through security purchases, Frank Nothaft, Freddie Mac vice president and chief economist, said in a statement.

The U.S. government has embarked on an aggressive plan to bring mortgage rates down to levels that will spur demand and help the hard-hit housing market begin to recover.

Thirty-year mortgage rates had mostly been on a downward trend since the Fed -- the U.S. central bank -- unveiled a plan to buy mortgage-backed debt in late November.

The Fed has set a goal to buy up to $1.25 trillion of agency MBS, $300 billion of Treasuries and $200 billion of agency debt in 2009. The purchases are part of efforts to lower borrowing costs.

The battered U.S. housing market, which is in the midst of its worst downturn since the Great Depression, is both the source of and a major casualty of the credit crisis. A recovery for the market could portend a turnaround for the United States, the world's largest economy.