U.S. Treasury prices slipped on Monday in quiet trading, pressured by a $62 billion sale of new coupon-bearing government debt this week and steady risk appetite following a strong U.S. jobs report last Friday.
Yields on U.S. long-term securities rose for a second straight day, helped as well by easing tensions between Russia and Ukraine, analysts said.
Officials from Ukraine and Russia met late on Monday in last-minute talks brokered by the European Union to resolve a dispute that could halt the flow of gas from Russia. Monday's talks follow a tentative rapprochement last week when newly installed Ukrainian President Petro Poroshenko and Russia's Vladimir Putin met in France at commemorations of the World War Two D-Day landings
U.S. bond supply, however, remained the focus of the week, with the $62 billion Treasury coupon auctions, beginning with Tuesday's $28 billion three-year note sale. That will be followed by the sale of $21 bln in 10-year notes on Wednesday, and $13 billion in 30-year bonds.
"Some of today's weakness is just prepping for the auction that's coming this week,'' said David Keeble, global head of interest rates strategy at Credit Agricole in New York.
"It's the long ones on auction, so you've got to put duration in the market and we're doing it now without much help from Federal Reserve purchases that we've had before.''
Read MoreFive years later, do we face a market 'melt-up'?
Benchmark 10-year notes were last down 5/32 in price to yield 2.61 percent, from 2.59 percent late on Friday.
For the first time since April 2010, Spanish 10-year yields fell below those of U.S. Treasurys. Spanish yields hit historic lows of 2.58 percent.
Italian five-year yields were also below U.S. equivalents, highlighting the policy divergence between the European Central Bank, which has launched further stimulus, and the Fed, which has been reducing its asset purchases.
Read MoreFed's Rosengren: No rate hike until goals achieved
The impending end of the Fed's quantitative easing has been helped by upbeat U.S. non-farm payrolls, which increased by 217,000 last month, returning employment to its pre-recession level.
prices were down 6/32 to yield 1.68 percent.
U.S. 30-year bonds fell 7/32 in price to yield 3.45 percent, from 3.43 percent late on Friday.
Investors are now looking to Tuesday's U.S. three-year note auction, which has seen mixed results in the past despite steady demand.
Barclays Capital in a research note said on a three-month moving average basis, domestic investment fund demand has increased to 26 percent since February, while foreign investor demand has declined by a similar proportion resulting in broker-dealers still absorbing 56 percent of the auctioned amount.
Read MoreGrowing market bullishness not a concern yet
The New York Federal Reserve, meanwhile, bought on Monday $0.97 billion in bonds with maturities ranging from February 15, 2036 through May 15, 2044. Offers totaled $4.559 billion.