May saw mortgage activity rise to its highest level this year, according to Mortgage Advice Bureau’s (MAB) latest National Mortgage Index.

Levels last month were up 25% on January, the broker reported.

Using data from more than 500 brokers and 800 estate agents, the National Mortgage Index found the total number of mortgage applications year-to-date was up 16% on 2011.

This increase is being driven in part by a surge in remortgage business, with the amount of remortgage applications 21% higher than this time last year.

“With average two-year fixed rate mortgages having risen month on month since September 2011 and three and five year fixes also both having risen month on month from December 2011, and with several lenders recently raising their Standard Variable Rates, it is not surprising we have seen an uplift in the number of remortgage borrowers,” said Brian Murphy, head of lending at Mortgage Advice Bureau.

“And with the average loan-to-value of remortgage borrowers reducing significantly during May it appears that a number of borrowers with high levels of equity, who have until now refrained from remortgaging, are now entering the market and taking advantage of what are still – by historic levels – extremely attractive rates,” he added.