Interest rates on Treasury bonds neared a 14-month high Tuesday, a sign that investors are growing nervous about how a closely watched jobs report later this week will affect the Federal Reserve’s massive economic stimulus program.

Analysts expect a government report Friday to show that 167,000 jobs were added last month, which would be an improvement over April and an indication of a strengthening economy.

That, in turn, could encourage the Fed to taper its stimulus program. The Fed has been buying $85 billion in bonds each month since the fall in an effort to keep long-term interest rates low and help the economic recovery.

Some Fed officials have said that the central bank should begin scaling back the program as early as this summer. The yields of 10-year government bonds have risen from 1.6 percent in early May to 2.13 percent on Tuesday. Bond yields rise as prices fall, indicating declining demand. And in recent days, there has been a spike in bond “shorts,” or bets that Treasury bond prices will fall further.

More than 80 percent of large mutual funds with at least $500 million in bond assets lost money in May. With bond prices falling, the funds assets are worth less. Their average loss was 0.91 percent, according to Lipper, a unit of Thomson Reuters, while the worst performers lost as much as 10 percent.

Bank of America is urging its clients to sell Treasurys and buy bank stocks instead, noting that “risks of a bond crash are high” and that “it’s hard to believe that the greatest bond bull market in history will end without some bloodshed.”

But Pacific Investment Management’s Bill Gross, manager of the world’s biggest bond fund, told his clients Tuesday that Treasurys are still the safest type of bond investments, advising them to get out of riskier bonds.

The timing of the slowdown in the Fed’s bond-buying program has divided its leadership. “The recovery of the U.S. economy needs to show much more progress” before the Fed changes its strategy, Fed Governor Sarah Bloom Raskin said Tuesday.

Esther George, president of the Federal Reserve Bank of Kansas City, however, warned that “waiting too long to acknowledge the economy’s progress and prepare markets for more normal policy settings carries no less risk than tightening too soon.”