More people in the UK are putting their properties on the market but in most cases, with London being the exception, there are not enough buyers, according to the latest report from Rightmove published last week.

The increased seller numbers has resulted in the biggest monthly jump in agents’ unsold stock since May 2007, up from 70 to 74 properties per branch, the report also shows.

As property supply is increasingly outstripping demand, this month’s jump in new sellers’ average asking prices of 1.7 percent (£4,032) looks misplaced. London remains the exception as buyer demand pushes asking prices to a new record of £431,013.

With base rate rises looming, sellers who are keen to sell in the spring window should adopt ‘serious seller’ tactics, according to Rightmove. There are a larger than normal number of bank holidays coming up in the UK because of Easter and the Royal Wedding and estate agents usually see slower activity at these times.

‘This is a clear indication that the number of properties available to buy is not being matched by the number of buyers able to proceed. With buyers still struggling to raise the necessary finance, the net result has been the biggest jump in unsold stock on agents’ books that we have recorded in nearly four years,’ said Miles Shipside, director of Rightmove.

‘While stock levels normally increase during the first half of the year, this is a larger increase than normal. With government cuts starting to bite and interest rate rises still expected in the second half of the year, those who are serious about selling should look to price more keenly in the spring selling season,’ he added.

This month, a weekly average of 28,390 properties came to market, an increase of 9% on April 2010 and up 28 percent on April 2009. With the latest Bank of England mortgage approval figures showing no year on year growth at 40,302 in February 2011 compared with 40,582 in February 2010.

The report also shows that average asking prices have increased 1.7 percent in April compared to the previous month. ‘In May 2007 when we last saw an increase in stock levels of this magnitude its impact was lower as mortgage financing was freely available and market conditions were more buoyant. It is against this backdrop of a substantial increase in available property supply that new sellers have pushed up their average asking prices to 1.7 percent higher than those recorded a month ago. This is the fourth consecutive monthly increase,’ said Shipside.

With national average asking prices now £13,412, or six percent, higher in the four months since the start of the year, sellers and estate agents should take serious note of the growing imbalance between seller supply and the seemingly static number of buyers who are ready, willing and able to proceed, according to Shipside.