Average house prices dropped in May for the third successive month, according to the latest Nationwide house price index the first time this has happened since 2009.
Nationwide Building Society said values dipped by 0.2% month-on-month in May, following a 0.4% decrease in April and a drop of 0.3% in March.
Across the UK, the average house price was £208,711 in May, marking a 2.1% year-on-year increase. A year earlier, price growth was more than double this rate, at 4.7%.
The data also shows regional variation. In London, there has been a fall in the luxury home market over the last 12 months because of a sharp rise in stamp duty and changes to capital gains tax rules for overseas investors buying UK residential property. However, prices are still rising in the West Midlands and Wales.
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Are price falls 'merely a blip'?
Robert Gardner, Nationwide's chief economist, said it is too early to know whether the slowdown is "merely a blip", a reflection of the squeeze on household budgets or due to mounting affordability pressures in key areas.
He said: "It is still early days, but this provides further evidence that the housing market is losing momentum. Moreover, this may be indicative of a wider slowdown in the household sector, though data continues to send mixed signals in this regard."
Mr Gardner said that "if history is any guide", the slowdown is unlikely to be related to uncertainty over the general election on Thursday 8 June.
"Housing market trends have not traditionally been impacted around the time of general elections," he said. "Rightly or wrongly, for most homebuyers elections are not foremost in their minds while buying or selling their home."
Mr Gardner said that despite the "unusually uncertain" outlook for the economy, the subdued level of building activity and the shortage of properties on the market are likely to help hold prices up. As a result, he believes a small increase in prices of about 2% is likely over the course of 2017.
Additional reporting by the Press Association.