Private rental prices paid by tenants have seen sharper increases in London and Scotland than elsewhere in Britain over the last year, official figures show.

Across Britain, rents increased by 1% in the 12 months to September. In London they lifted by 1.5%, while in Scotland the figure was 1.4%, according to the Office for National Statistics (ONS).

The average rental price increase seen by tenants across Britain over the last year is below the annual rise in living costs generally. The Consumer Price Index (CPI) measure of inflation fell to 1.2% in September, reflecting the impact of a supermarket price war.

The ONS figures show that in England as a whole, rents have lifted by 1% over the last year, with London seeing the fastest annual growth there, followed by the South West, which has seen a 1.1% increase.

If London were taken out of the figures, rents would have only increased by 0.8% across England over the last year, the ONS said.

The smallest increase in rental costs in England has been seen in the North West, where rents have edged up by 0.3% over the last year, followed by the North East and Yorkshire and the Humber, which both recorded annual increases of 0.4%.

In Wales, rents edged up by just 0.2% in the 12 months to September.

The findings were released as research by the Royal Mail suggested that following the strong increases seen to house prices this year, rental sector tenants are becoming less optimistic about their prospects of being able to buy their own home.

The research carried out among around 13,000 people who had used the Royal Mail's redirection service found that across the UK, 36% of renters surveyed said they are becoming more optimistic about the prospect of buying their own home in the future. This figure is down from 42% of renters who expressed this view when similar research was carried out six months earlier.

The Royal Mail found that people renting their home in the Midlands were the most positive about their prospects for buying a home, followed by people renting in the North East, while those living in the South East were the least optimistic about their chances of getting on the housing ladder.

The study also found that 38% of renters surveyed in Wales said they are more optimistic about buying a property compared to last year. In Scotland, the figure is 34%.

Not being able to raise a big enough deposit, the struggle to meet lenders' toughened mortgage criteria and finding a home that they actually wanted to buy were cited by renters as common barriers to buying, the Royal Mail found.

The ONS figures are currently classed as "experimental" statistics which means that they form part of a new series of figures which is currently undergoing evaluation.

A separate rental index run by lettings network LSL Property Services, which owns chains Your Move and Reeds Rains, recently found that a verage rents across England and Wales rose to a new all-time high of £768 per month in September. That index is based on rents achieved on around 20,000 properties.

Housing Minister Brandon Lewis said: "Under this Government rents have fallen every year in real terms across the country.

"We're working to build a bigger, better private rented sector. By boosting supply, through a £1 billion Build to Rent fund which will deliver up to 10,000 new homes for rent and through a model tenancy agreement we are giving tenants the confidence and choice to get a fair deal.

"This is being done without the need to wrap the industry in red tape which would only force up rents and slow down investment."