The latest global cost-of-living survey by The Economist Intelligence Unit ranks Melbourne as the world's sixth most expensive city.

It remains a more affordable city to live in than Sydney - but only slightly. The NSW capital ranked fifth in the survey.

"The long-term rise in the relative cost of living in Australia, driven by sustained strengthening of the Australian dollar, has cemented the positions of cities like Sydney and Melbourne as top-ten staples," the report says.

"This comes despite the fact that 10 years ago both cities were cheaper than New York."

Based on surveys conducted in March and September last year, the average cost of a one kilogram loaf of bread in Melbourne was $4.22 in US dollar terms, compared to $4.96 in Sydney.

The average cost of a bottle of wine in Melbourne was US$23.32, up from US$22.28 the previous year and US$19.45 five years earlier.

The average price of a litre of unleaded petrol also rose year-on-year, from US$1.35 to US$1.42.

The prices of items were converted into US dollars using a prevailing exchange rate at the time and weighted to achieve comparative indices.

Other Australian cities also made the top 50 most expensive cities, with Brisbane coming in at 21.

Perth and Adelaide tied at 24, with Perth having fallen three places and Adelaide jumping 13 places.

Singapore retained its position as the world's most expensive city, followed by Paris, Oslo and Zurich.

New York clocks in at the relatively modest position of the 26th most expensive city.

At the other end of the scale, the Pakistani city Karachi is listed the world's least expensive city.

The survey ranks 133 cites over five continents by comparing 400 prices across 160 products and services including housing, transportation, food, clothing, household goods and entertainment.

Intelligence Unit analyst Jon Copestake said it was rare for the top five expensive cities to remain unchanged as they had in the bi-annual survey.

"It disguises some significant global drivers that are impacting the cost of living everywhere," he said.

"In fact, a look at the data six months ago would have shown a different top five, and things are changing quickly, especially with the fall in oil prices.

"Re-basing the survey to today's exchange rates would put Zurich top, highlighting how fluid the global cost of living has become."

The 10 most expensive cities in the world

1. Singapore
2. Paris, France
3. Oslo, Norway
4. Zurich, Switzerland
5. Sydney, Australia
6. Melbourne, Australia
7. Geneva, Switzerland
8. Copenhagen, Denmark
9. Hong Kong
10. Seoul, South Korea

The 10 cheapest cities in the world

1. Karachi, Pakistan
2. Bangalore, India,
3. Caracas, Venezuela
4. Mumbai, India
5. Chennai, India
6. New Delhi, India
7. Tehran, Iran
8. Damascus, Syria
9. Kathmandu, Nepal
10. Algiers, Algeria