Among the most expensive cities around the globe Armenian capital Yerevan in 2011 reduced its positions by 3 ponts and ranks the 167th, according to Mercer Human Resource Consulting research.

The 2011 Cost of Living survey by Mercer is based on several criteria, including food and entertainment.

Luanda, Angola's capital, has been named the world's most expensive city for expats for the second year in a row.

In Luanda, renting a luxury two-bedroom unfurnished apartment costs an average of $7,000 per month, compared to $4,300 in New York, $3,345 in Shanghai, $2,456 in Rome and $1,800 in Buenos Aires.

Angola's oil reserves do at least mean that gas is cheap in Luanda -- 59 cents per liter, compared to 87 cents in New York and $1.12 in Shanghai.

According to a new survey, Tokyo is the next most expensive, with N'Djamena, in Chad, the third-most expensive city for expats. The survey covers 214 cities across five continents and compares the cost of more than 200 items in each, including housing, transport and food.

Currency prices can affect the results. All cities surveyed are measured against New York, with currency movements measured against the U.S. dollar.

However, Constantin-Metral said currency prices were not a factor in the high placings of Luanda and N'Djamena, according to CNN.