NEW YORK (Reuters) - Applications for U.S. mortgage refinancing rose last week to their highest level in over three years as 30-year home loan rates sunk to their lowest since 2013, according to data from an industry group released on Wednesday.

Mortgage rates have fallen with U.S. Treasury yields in the wake of Britain's surprise vote to exit the European Union on June 23. This fed anxiety about global economic growth and wagers on more stimuli from overseas central banks, sending U.S., European and Japanese government bond yields to historic lows.

The Mortgage Bankers Association said its seasonally adjusted index of refinancing applications climbed 11.2 percent in the week ended July 8 to the highest level since June 2013. This followed a 20.8 percent jump the prior week.

However, the group's seasonally adjusted gauge on loan requests for home purchases, a leading indicator of home sales, was unchanged on the week.

The share of weekly refinancing requests increased to 64.0 percent of total applications from 61.6 percent the previous week, the Washington-based group said.

The surge in refinancing activity propelled total weekly applications 7.2 percent up on a seasonally adjusted basis to its highest level since June 2013, according to MBA data.

The average rate on "conforming" 30-year home mortgages, or loans with balances of $417,000 or less, declined to 3.60 percent, the lowest since May 2013, from 3.66 percent the previous week, MBA said.

The figure is close to the historic low of 3.47 percent set in December 2012.

The benchmark 10-year Treasury yield <US10YT=RR> touched a record low of 1.321 percent last week. It was 1.471 percent on Wednesday, down 4 basis points from late on Tuesday, according to Reuters data.

(Reporting by Richard Leong Editing by W Simon)