According to data from the Office of National Statistics (ONS), rents grew 3.5 per cent over the past year in the south east, compared to a rise of three per cent in London.
Richard Connolly, chief executive of rent-to-buy homes provider Rentplus, said the data reflects the fact that rent hikes are "firmly a national issue".
"The struggles are numerous with aspirant home owners in the current climate also facing rising fuel bills, low salary growth and low interest rates from savings accounts," Connolly said.
In Britain as a whole, prices were up 2.4 per cent in the year to July. However, excluding London rents, private rental prices in Britain grew by 2.1 per cent.
The following chart shows how London pulls up the national average; the graph tracks index values that show how rent prices have changed in relation to a base level set January 2011.
Connolly said: "The annual jump in private rental prices reported today is a stark reminder of the struggles that many people living in private rented homes are facing in saving a deposit to buy their first home - which remains the biggest barrier to ownership."