Halifax’s House Price Index has come under scrutiny for the second month in a row after posting what some said was a highly questionable 5.2% average annual increase in property values.

This suggests values are growing at their fastest rate for two years and follows a 5% annual boost reported by the lender for April.

One disbelieving critic said he wanted whatever Halifax was smoking.

Halifax said average values were up 0.5% on a monthly basis to reach £237,837 in May.

Halifax’s data has come under scrutiny after it reported a 5.9% monthly increase in February.

Its May figures compare with Nationwide’s data for the same month showing prices rose just 0.6%.

Russell Galley, managing director of Halifax, said: “Despite the ongoing political and economic uncertainty, underlying conditions in the broader economy continue to underpin the housing market, particularly the twin factors of high employment and low interest rates.”

Commenting on the figures, Brian Murphy, head of lending for the Mortgage Advice Bureau, said: “The year-on-year increase is significant, but this is likely to be the result of those areas of the country which are experiencing more buoyant conditions, such as the midlands, the north and Wales, contributing to an increase in the average figure.

“Also, it’s possible that the lower than average figure for the same period last year has contributed towards a slightly skewed annual increase.”