UPDATE 4-U.S. Fed sees rates near zero for extended period

* Fed repeats to keeps rates low for "extended period"

* Fed sees economic activity continuing to pick up

* Commitment to buy agency debt trimmed to $175 billion

* Fed gives more upbeat assessment on household spending (Recasts with Fed decision)

By Mark Felsenthal and David Lawder

WASHINGTON, Nov 4 (Reuters) - The U.S. Federal Reserve on Wednesday expressed growing confidence that an economic recovery was building, even though it stuck to its commitment to keep borrowing costs near zero for "an extended period."

In a unanimous vote, the Fed's policy-setting Federal Open Market Committee decided to keep its benchmark federal funds rate unchanged in a range of zero to 0.25 percent, as expected.

It said the economy had "continued to pick up" since its last meeting in September, but expressed concern that the economy's recovery was likely to be sluggish.

"Household spending appears to be expanding but remains constrained by ongoing job losses, sluggish income growth, lower housing wealth, and tight credit," the U.S. central bank said in a statement outlining its decision.