The housing market continues to defy fears of a post-referendum slump after sellers’ asking prices hit a new record high of more than £313,000 on average in April.

Across England and Wales, the average price tag on a property being put on the market increased by £3,547 – or 1.1% month-on-month – to reach £313,655.

The figures were released by property website Rightmove, whose records go back to 2002. It said the average asking price in April surpassed a previous high of £310,471 reached in June 2016.

Some economists have forecast static prices this year of 2% at most in response to a squeeze on disposable incomes from rising inflation and slowing wages growth. But others have argued the failure to increase the housing stock will keep prices increasing at nearer 5%.

Rightmove said strong numbers of house sales being agreed – at levels not seen since before the credit crunch – have helped to keep pushing asking prices upwards.

Miles Shipside, director of Rightmove, said there were signs of a “strong spring market”, which should help to offset any jitters in the market before the general election on 8 June.

The first-time buyer sector was driving the price increases, Rightmove said, after changes to previously generous tax rules deterred buy-to-let investors from competing for similar homes.

Asking prices in this market are up by 6.5% year-on-year, with the typical price tag on a first-time property – one with up to two bedrooms – now at a record high of £194,881.

Across all sectors, asking prices are up by 2.2% year-on-year across England and Wales. Rightmove said the annual pace of asking price growth had generally slowed and was now at its lowest since April 2013.

London and the north-east were the only regions in the study where average asking prices were lower than a year ago. In the capital they were downl 1.5% annually, at £636,777 on average, while in the north-east they were down 0.7%, at an average of £150,350.

Eastern England has seen the strongest growth over the last year, with a 5.3% uplift taking the average property price there to £349,269.

The West Midlands reported the next strongest, with a 5% increase pushing average prices to £215,784. In Wales, they were up by 4% year-on-year to reach £186,172 on average.

Shipside said the number of sales being agreed was the highest for this time of year since 2007.

Last year, the chancellor gave a year’s notice of phased reductions in tax benefits for buy-let-investors. First-time buyers appear to have been the main beneficiary, though a higher rate of stamp duty on second homes, which came into effect this month, also had the effect of spurring sales to people from purchasing an additional property.

Shipside said: “Strong buyer activity this month has led to 10% higher numbers of sales agreed than in the same period in 2016. This large year-on-year disparity should be viewed cautiously as the comparable timespan in 2016 saw a drop in buy-to-let activity with the additional second home stamp duty.”

But he said the figures for agreed sales were also up by 3.8% when compared with two years ago. “With the growth in household numbers and new-build supply struggling to keep pace, demand is strong and has led to the highest sales agreed numbers at this time of year since the heady pre-credit crunch levels,” he said.