U.S. economy expanded at a 2.8 percent in the fourth quarter

Gross domestic product expanded at a 2.8 percent annual rate in the fourth quarter, the Commerce Department said on Friday, a sharp acceleration from the 1.8 percent in the prior three months.

Soft underlying demand and a sharp slowing in core inflation supported the Federal Reserve's decision this week to keep in place an ultra easy monetary policy to nurse the recovery.

The economy got a temporary boost from the rebuilding of inventories, which logged the biggest increase since the third quarter of 2010.

Excluding inventories, the economy grew at a tepid 0.8 percent rate, a sharp step-down from the prior period's 3.2 percent pace and a sign of weak domestic demand.