There are big regional differences in house price growth

The new index - to be issued monthly - aims to provide a clearer indication of the market than other surveys, the government hopes.

The average UK house price is now �156,273, the index shows, up from �138,042 a year ago.

But the latest survey from property website Rightmove found asking prices for UK properties growing at an annual rate of just 9.1%, with prices falling 0.6% in August compared with the previous month.

Limitations

The data for the new government index is collated by the Office of the Deputy Prime Minister.

The major drawback is that the new reading is not very timely - it will only appear two months in arrears In search of the perfect index

It said the move to produce the figures on a monthly basis followed calls from the Bank of England and the Treasury for an official monthly house price index to help their forecasting.

While other market surveys are based on prices agreed when mortgages are advanced, the government's version covers actual prices when the transactions are completed.

But limitations in the data on which it is based means it will only monitor about a quarter of the UK's mortgage-funded deals each month - and will not include properties bought for cash.

The new index shows that annual house price inflation rose to 14.6% in July from 13.4% in June.

AVERAGE HOUSE PRICES England �166,669 Scotland �93,778 Wales �103,669 Northern Ireland �100,246 Source: Office of the Deputy Prime Minister

But there were big regional differences across the UK, with annual house price inflation highest in the North East of England at 24.4% and lowest in London at 9.4%.

But when it came to average house prices the situation was reversed, with the highest average price being �241,818 in London and the lowest �96,620 in the North East.

First-time buyers paid an average price of �120,830 in July, up from �114,699 the month before.

Opinion split

The Rightmove survey found average asking prices fell by 0.6% in the month to 6 September, the first monthly decline since January and the sharpest since the beginning of 2002.

The fall dragged the annual rate of house price inflation from 12.4% the previous month to 9.1%, the first time it has dipped below the symbolic 10% level since the Rightmove index was launched a year ago.

Rightmove's figures are at odds with recent surveys from mortgage lenders Halifax and Nationwide, which both calculated that house prices rose by slightly more than 1% in August.

Halifax and Nationwide results also differ from Rightmove's in that their latest estimates of annual house price inflation are far higher at 19.2% and 16.6% respectively, although they agree that the rate of increase is slowing.