Swiss city dwellers enjoy the highest quality of life in the world, while inhabitants of Baghdad and Khartoum live in some of the worst conditions, according to a survey.

The study of 218 cities, conducted by London-based human resources consultants William M Mercer, looked at 39 factors governing quality of life, including politics economics and environment, personal safety and health, education, transport and recreation.

Each city was compared with New York which was given 100 points, putting it in 50th place. Other US cities were hit by their high crime rates and personal security problems, with Honolulu ranking highest with 104 points.

The four top cities - Vancouver, Zurich, Vienna and Bern - scored 106.

Other cities in the top 10 are Sydney, Geneva, Auckland, Copenhagen, Helsinki and Amsterdam.

London came in at number 34 with 101.5 - its quality of life affected by its unfriendly climate and traffic congestion. Tokyo and Paris were marginally ahead on 102.5.

The four least desirable cities were Baghdad and Khartoum with 33, Pointe Noire in Congo-Brazzaville, with 30.5, and the lowest ranking Brazzaville, the capital of Congo-Brazzaville, with only 23 points. Mercer attributed Brazzaville's low living standards to the continuing civil war in the region.

"At the very top of the scale there is little to choose between the highest-scoring cities," said Jasbir Singh, European Partner with Mercer.

"Crime levels, transport and education services are what can make the difference," he explained.

"It is in the developing countries where the real variables can be seen, affecting personal safety, hygiene and the basic comforts of living."