Yields mostly flat after Fed Beige Book report

Bond prices were unchanged on Wednesday after the Federal Reserve said the economy continued to expand across most regions and sectors from early January through mid-February, with auto sales and consumer spending rising in most Fed districts.

In its Beige Book report of anecdotal information on business activity collected from contacts across the nation, the central bank said wage pressures were moderate across most districts.

Benchmark 10-year U.S. Treasury notes were yielding 2.12 percent, unchanged from Tuesday. U.S. 30-year bonds were also flat with the yield at 2.71 percent.

U.S. Treasurys seesawed between positive and negative territory earlier after a weaker-than-expected reading on U.S. private payrolls growth contrasted with stronger-than-expected U.S. services sector data and created uncertainty ahead of Friday's U.S. jobs report.

U.S. private employers added 212,000 jobs last month, lower than economists' expectations for 220,000, according to a Reuters poll. The figure was also lower than January's upwardly revised figure of 250,000.

Read MorePrivate job growth slowest in six months: ADP

The Institute for Supply Management, meanwhile, said its services index was 56.9 in February, up slightly from 56.7 in January and beating analysts' expectation for a reading of 56.5, according to a Reuters poll.

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Economists polled by Reuters expect the U.S. nonfarm payrolls report to show employers added 240,000 jobs in February, down from 257,000 in January. Wednesday's reports reinforced traders' reluctance to make major bets ahead of the jobs data.

"The data today probably increased the angst around the nonfarm payrolls number," said David Coard, head of fixed-income sales and trading at Williams Capital in New York.

Read MoreFed's Evans wants no rate hikes until 2016

The European Central Bank meets on Thursday, which will give investors more details on its 1 trillion euro ($1.118 trillion) government bond-buying program, which begins this month.

The ECB meeting underscored the attractiveness of higher U.S. Treasury yields compared to European yields and helped support Treasurys prices. German 10-year Bund yields were last at 0.37 percent, not far from a record low of 0.28 percent touched on Feb. 26.

The ECB meeting "makes the market focus more on global fixed income, and whenever you're thinking of global fixed income now, Treasuruys stand out as much higher yield," said Jake Lowery, portfolio manager at Voya Investment Management in Atlanta.