WASHINGTON – Rates on 30-year home loans rose this week and were poised to go higher as investors demanded higher rates for long-term government debt, which is closely tied to mortgage rates.

Mortgage finance giant Freddie Mac said Thursday that average rates on 30-year fixed-rate mortgages rose to 4.91 percent this week, from an average of 4.82 percent a week earlier. Rates in Freddie Mac’s survey have been below 5 percent for more than two months. If they rise higher, that will diminish the appeal of refinancing for many borrowers.

The yield on the Treasury’s 10-year note – a key benchmark for home mortgages and other kinds of loans — reached its highest level since November earlier this week.

The worry is that rising bond yields could drive mortgage rates higher and increase the cost of borrowing for businesses. That could short-circuit the nation’s efforts to emerge from a deep recession and the worst housing crisis in decades.