The Government is to publish its own monthly house price index from the beginning of next summer.

The Office of the Deputy Prime Minister John Prescott (ODPM), said the National Statistics House Price Index, plans for which were unveiled in August, would be based on at least 30,000 sales each month, about a third of all mortgage completions.

But it denied it was introducing the survey because it was worried figures on house price rises put out by Halifax and Nationwide were stoking the property boom.

It said the index was simply an expansion of the quarterly one that has been published since 1968, based on a five per cent sample of completions from 49 lenders.

After improvements in technology, many lenders had indicated they would be prepared to provide data on all their completions, making the sample big enough for the index to be expanded from a quarterly one to a monthly one.

But ODPM said the Nationwide and Halifax indexes, which are based on the lenders' own mortgage approvals, would still have an important role to play, as they reflected house prices six to eight weeks before completion and provided an early indication of house price trends.