Around 22.4% of mortgage approvals were for first-time buyers in May, up from 20.2% in April.
Overall approvals also rose by 6.4% from the month before to 66,479 on a seasonally adjusted basis.
Richard Sexton, director at e.surv, said: “There was strong growth in the mortgage market in May, with approvals rising significantly compared to April.
“Mortgages are at the forefront of the national conversation, with many people assessing their options and looking to fix in this rising interest rate environment.
“While the base rate may have stayed at 0.5% in May, speculation continues about the next increase, which appears to be coming sooner rather than later.”
Meanwhile the number of small deposit loans being approved increased from 13,429 in April to 14,891 in May.
Sexton added: “We have seen a sharp increase in the number of small deposit borrowers this month, which will be a big confidence boost to others looking to get on the ladder soon.
“This is the second successive month we have seen a large rise, suggesting now is a great time if you have a small deposit.”