For existing owners, house prices increased by 11.2 per cent for the same period. However, the August 2014 figure of 12.9 per cent is down from an increase of 13.5 per cent in July 2014.
The ONS HPI revealed the average price paid for a house by a first-time buyer was £210,000. The average price for properties bought by former owner-occupiers (existing owners) increased by 11.2 per cent in the year to August 2014, up from an increase of 10.9 per cent in July 2014.
This represents the highest annual increase for existing owners since October 2007, when prices increased by 11.4 per cent. In August 2014, the average price paid for a house by a former owner-occupier was £315,000.
Amongst other key findings from the research, UK house prices increased by 11.7 per cent in the year to August 2014 overall, which is unchanged from the year to July 2014. Average house prices increased by 0.6 per cent between July and August 2014 on a seasonally adjusted basis.
The ONS HPI data also revealed that house prices are increasing strongly across the UK, with prices in London showing the highest growth again.
Annual house price increases in England were driven by an annual increase in London of 19.6 per cent and to a lesser extent increases in the south east -12.3 per cent - and the east was 11.6 per cent.
Excluding London and the south east, UK house prices increased by 7.8 per cent in the 12 months to August 2014.
House price annual inflation was 12.2 per cent in England, 4.7 per cent in Wales, 6.7 per cent in Scotland and 9.6 per cent in Northern Ireland.
The new data on house prices comes as the ONS released a consultation on the development of a single official house price index, amid signs of confusion at various data sources and indices that give wildly differing accounts and outlooks on the housing market.
The consultation is seeking views regarding the ONS’ proposed methodology for a new index for official house price data.
The ONS and Land Registry already publish statistics, along with separate registers in Scotland and Northern Ireland.