By Jonathan Davies

House prices are being pushed up due to a lack of people selling their houses, according to the Royal Institute of Chartered Surveyors (Rics).

Rics said instructions by new sellers had fallen "deeper into negative territory". The number of people selling their homes has fallen in eight of the past nine months, and new instructions are falling at the fastest rate since May 2009.

Despite the lack of available houses, the number aspiring buyers inquiring has not fallen.

Simon Rubinsohn, Rics chief economist, said: "It is conceivable that the decisive outcome to the election could encourage a pick-up in instructions to agents and ease some of the recent upward pressure on house prices, but it is doubtful that this will be substantive enough to provide anything more than temporary relief.

"Alongside an increased flow of second hand stock, it is absolutely critical that the new government focuses on measures to boost the flow of new build."

According to the Office for National Statistics (ONS), house prices have been flat since July 2014. But recent figures from Halifax and Nationwide suggest that prices are rising again.

The need for more housebuilding has been widely accepted by politicians. But Rics head of policy Jeremy Blackburn says the UK is heading for a national emergency.

"The last time we were building 300,000 homes was in 1963 under Harold Macmillan's Conservative government, which utilised both public and private building," he said.

"We need a coherent and coordinated house building strategy across all tenures.

"Introducing demand-side measures, such as extending 'Right to Buy', will not see the Conservatives deliver on their promise of one million homes by 2020," he added.