Although the property website admits the traditional Easter home moving season contributed to the figures, its analysts claim that a "unique combination" of factors contributed to the five-year high.
Miles Shipside, Rightmove's commercial director, said: "Sellers' asking prices provide one of the earliest indicators of which way the market is headed, and while a boost is to be expected around Easter, £8,000 in a month is the largest amount we have ever recorded."
Today's research reveals that the average price of a house in the UK is now £236,490, with every region experiencing "major increases".
But Mr Shipside warned: "As prices go higher, fewer buyers can afford to get on the ladder or trade up, and that will restrain ongoing increases in many parts of the country. More affluent areas will remain the exception however."
The commercial director went on to caution that ahead of the long-awaited introduction of Home Information Packs (Hips) at the beginning of June, many estate agents were persuading sellers to rush the housing market beforehand to avoid incurring extra costs.
"On the cusp of the most significant legislative change to the home moving process the market has ever seen, it is of huge interest how home movers and those in the industry will react," he explained.
"The early indications are that the spring timing of the run in to Hips implementation, combined with the current market conditions, will lead to a distortion of traditional market forces over the coming months," Mr Shipside continued, adding that analysts were expecting a "feeding frenzy" ahead of the summer.
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