The gap between the country's most and least affordable homes is growing larger, official figures show.

In the London borough of Westminster, the average house price cost 24 times the gross annual average salary in 2014 - meaning it could be described as the least affordable area in England and Wales in which to buy a house - the Office for National Statistics (ONS) said.

At the other end of the spectrum, the average house price in Blaenau Gwent in Wales, at £75,000, is four times greater than the average salary of £18,709 - making it the most affordable place to buy a home.

Homes in Blaenau Gwent have become more affordable when compared with earnings in recent years, while those in Westminster - a hotspot for wealthy overseas investors - have spiralled further out of kilter with residents' salaries.

The average home in Westminster was worth £875,000 in 2014, while the average salary there was £36,519.

In 2007, the average home in Blaenau Gwent cost nearly five-and-a-half times the average wage, according to the ONS's Housing Summary Measures Analysis.

Meanwhile, in 2007 a home in Westminster cost 14 times the average wage. Going back further, in 2004 a home in Westminster cost just under 12 times the average wage - meaning that the affordability ratio there has doubled in the space of a decade.

The ONS said that since 1995, the price paid for houses in the least expensive 10% of areas in England and Wales has increased by three times the average 1995 price.

Meanwhile, the most expensive 10% of areas have seen price rises of more than four times the average 1995 price.

Across England and Wales in 2014, average house prices ranged from just under £1.2 million in Kensington and Chelsea to £75,000 in Blaenau Gwent.

The average house price for England and Wales overall in 2014 was £194,955, which was 8.78 times the typical wage. In 2002, the house price-to-earnings ratio was smaller, at 6.4.

Over the last 20 years, the local authorities with the highest average house prices have tended to be in London and the South East, while local authorities with the lowest prices tended to be distributed across the other English regions and Wales, the report said.

The ONS said that people who earn more are more likely to be able to afford to buy their own home, and this can increase the demand for owner-occupied housing, which in turn pushes up average house prices.

But it named the local authority of Blaby in the East Midlands as an exception to the general trend. In 2014, the average gross annual salary in Blaby was £25,637, which is in the highest 20% of all local authorities.

But the average house price in Blaby, at £170,000, was below the England and Wales average house price, making Blaby a relatively affordable area to own a home.

The ONS said: "One explanation for this is that some of the residents of Blaby work in other local authorities in which average salaries for workers are higher, leading to an increased average income of Blaby residents relative to house prices."

Housing and Planning Minister Brandon Lewis said: "Our affordable housebuilding efforts have exceeded ambitions and delivered more than 260,000 affordable homes, providing new quality homes that are available to rent or to buy through our affordable home ownership schemes.

"We're also determined to ensure that anyone who works hard and aspires to become a homeowner has the opportunity to do so. Over 200,000 households have been helped to purchase a home since spring 2010 through Government backed schemes including Help to Buy and Right to Buy."