Bernanke says U.S. growth still restrained

In Congressional testimony that made no direct reference to the near-term outlook for benchmark interest rates or the vow to keep them really low for an "extended period", Bernanke focused mostly on barriers to further growth.

"Significant restraints on the pace of the recovery remain, including weakness in both residential and nonresidential construction and the poor fiscal condition of many states and local governments," Bernanke told the Joint Economic Committee in prepared remarks.

He did cite encouraging signs that layoffs are slowing and employment has turned up.

But overall, his comments still suggested some cautiousness about the recovery, despite data on Wednesday showing a sharp 1.6 percent increase in March retail sales.

"Further economic expansion will depend on continued growth in private final demand," Bernanke said.