Darwin has topped a list of the most expensive cities in Australia to rent a house or unit.

A report released by the Australian Property Monitors for September showed that the average weekly rent for a house had increased by 4.2% over the past month to $500. The figures showed that this was $50 higher than the median rent for a similar property in Sydney, which came in second.

Units in Darwin also topped the list, with the report revealing that the median rent was $440, an increase of 10% from 2008 figures. The stats are good news for the city's property investors who are now enjoying the highest average gross rental yields in the country at 5.7%.

Australian Property Monitors' economist Matthew Bell pointed out that the average rental growth of 1.3% in the 12 months to September was the lowest since 2005, and was far below the previous two years' growth rate average of 14%.

Bell said: "For the second consecutive quarter, rents remained flat overall with falls in Sydney and Perth offsetting small rises in Brisbane, Hobart, Darwin and Canberra.' He added that most of the factors that moved the market did so in favour of renters, especially in the first September quarter.