(Bloomberg News) A group including former Republican government officials and economists urged Federal Reserve Chairman Ben S. Bernanke to halt his expansion of monetary stimulus, saying it risks an inflation surge.

"The planned asset purchases risk currency debasement and inflation, and we do not think they will achieve the Fed's objective of promoting employment," said the letter, signed by 23 people including Cliff Asness, who runs AQR Capital Management LLC, one of the world's biggest hedge funds; Stanford University Professor John Taylor, creator of a monetary-policy formula used by the Fed; and Douglas Holtz-Eakin, a former Congressional Budget Office director.

The letter increases pressure on Bernanke, whose November 3 decision to buy $600 billion of Treasurys in a bid to reduce unemployment has been criticized by Republican politicians and officials in Germany, China and Brazil. Bernanke was defended today by allies including Bank of Israel Governor Stanley Fischer and Princeton University Professor Alan Blinder.

"We disagree with the view that inflation needs to be pushed higher, and worry that another round of asset purchases, with interest rates still near zero over a year into the recovery, will distort financial markets and greatly complicate future Fed efforts to normalize monetary policy," the letter said.

The missive will be published in tomorrow's editions of the Wall Street Journal and New York Times, said Jennifer Pollom, a spokeswoman for Economics 21, a Washington research group whose logo is on the letterhead. Two signers, Kevin Hassett and Amity Shlaes, are columnists for Bloomberg News.

The letter is an effort to "stop a bad idea," Columbia University Professor Charles Calomiris, a signer of the letter, said today in a Bloomberg Television interview.

Fischer, who advised Bernanke on his dissertation at the Massachusetts Institute of Technology in the 1970s, said today on Bloomberg Television's "Surveillance Midday with Tom Keene" that the Fed is taking "a standard monetary policy action." Blinder, a former Fed vice chairman, said in a Wall Street Journal opinion article that Fed critics are "the economic equivalent of the Flat Earth Society."

David Blanchflower, an economics professor at Dartmouth College in Hanover, N.H., and a former Bank of England policy maker, said the criticism "shows very little understanding of how monetary policy makers behave."

"The Fed is the only show in town," Blanchflower, a Bloomberg News columnist, said on Bloomberg Television's "InBusiness with Margaret Brennan." The letter is "dangerous politics, playing with an economy that is fragile," he said.