Mortgage lending by the big banks hit a new all-time record of #18.23 billion, 27 per cent more than in May last year and an 18 per cent jump over April, when there were fewer working days.
Allowing for repayments, the British Bankers' Association said the banks' net mortgage lending rose by #5.73 billion, more than in any month for two years and up on the recent monthly average of #5.07 billion.
The number of new mortgages approved, but not yet paid out, for house purchase - as opposed to re-mortgages - was 20 per cent more than in May last year and 33 per cent higher by value.
Re-mortgages grew less strongly, with the number rising by only eight per cent year, though the total value was 28 per cent higher.
But the number of mortgages approved for equity withdrawal fell by seven per cent, while their total value was one per cent lower.
"Although numbers of approvals are still well below the levels of early 2004, the record level of gross lending and stronger net lending in May shows mortgage market activity to be healthy," said David Dooks, director of statistics at the BBA.
He pointed to a much more mixed pattern in unsecured lending. Credit card repayments outstripped new borrowing of #7.682 billion in May, so that seasonally adjusted net lending on plastic dropped by #251 million, after being flat in recent months.
Against that, net lending on personal loans and overdrafts jumped to #699 million from an average of #294 million in recent months.
Howard Archer, an economist at Global Insight, commented: "The robust BBA mortgage lending and approvals data for May indicate that the housing market upturn is still alive and kicking, following signs that it could be starting to falter.
"This suggests that house prices will see further strength in the near term. But we remain doubtful they can sustain strong increases for an extended period."