Buy-to-let lending for house purchases increased by 58% to £900m (7,500) loans, while remortgaging climbed by 64% to £1bn – a total of 6,600 loans.

George Spencer, chief executive officer of lettings agent Rentify, said: “Buy-to-let goes from strength to strength with nearly a 50% uplift in the volume of lending compared with the same month last year.

“We have seen a dramatic uplift in business in this first quarter which is likely to filter through to stronger lending figures in coming months.”

Spencer said cheap mortgage rates and an increase in appetite among lenders were playing a part.

But he said it also showed that landlords were being wise with their money keen not to pay over the odds for advertising, letting and property management services.

And the increased choice of products available to landlords is allowing them to shop around to secure the best deal.

The number of buy-to-let mortgage products reached an average of 586 giving landlords, on average, 152 more than in Q1 2013, figures from the Mortgages for Business index have shown.

And the index highlighted the growing strength in the remortgage market.

In quarter one this year 65% of standard buy-to-let transactions were remortgages rather than new purchases.

Landlords owning more complex properties are also remortgaging at an increasing pace.

Three quarters (75%) of transactions were against Houses in Multiple Occupation compared to 71% in the previous quarter and 69% in Q1 2013.

Meanwhile remortgages made up 81% of transactions involving larger, multi-unit freehold blocks up sharply from 69% last quarter and 75% compared to the same quarter in Q1 2013.

David Whittaker, managing director of Mortgages for Business, said: “Landlords know that exceptionally low interest rates can’t last forever. But now they need to act on that instinct.

“The Bank of England will almost certainly raise interest rates before the next general election. And that will have a sharp effect on anyone caught out in less than twelve months’ time.”

Whittaker said switching to a five year fixed-rate deal is important while these remain so affordable.