June buy-to-let sales were 28.6% lower year-on-year but still rose by 3% from the month before to reach £2.7bn, Equifax Touchstone analysis shows.
Residential mortgage sales were more consistent, growing by 4.4% from last year and by 2.6% from the previous month to £13.2bn.
Iain Hill, relationship manager at Equifax Touchstone, said: “June was another strong month for mortgage sales, despite an anticipated drop ahead of the EU referendum.
“Now an exit has become a reality, the really interesting stats to watch will be the July sales. There are a myriad of factors affecting house buying decisions and people will be weighing these up very carefully before deciding to take the plunge.
“The market is expecting sales to fall, but the extent of the impact is much harder to predict. We anticipate that lenders will react quickly and decisively to support sales, encouraging buyers with competitive new deals at lower rates.”
London saw the biggest decline in residential sales in June, dropping 3.8% from May.
The average value of a residential mortgage in June was £191,577 (2015: £185,553), and £161,102 for buy-to-let (2015: £156,584).