Campbelltown, Fairfield, Liverpool, Maitland and Canterbury are the top 5 Rental Hotspots in Sydney, according to new research.

In the past five years, Rental rates in each location have accelerated faster than anywhere else in the Greater Metropolitan Region, PRDnationwide revealed.

The city of Sydney still has the highest Rent for one and two-bedroom flats, at $500 and $670 per week respectively, but "savvy investors" are moving outside of the main town, according to the Australian firm's research.

"Investment opportunities also exist in areas outside the Metropolitan Area, where strong demand and limited supply of units maintains the pressure on rent prices," analyst Oded Reuveni-Etzioni told Property Wire.

Woollahra, Canada Bay and North Sydney were also highlighted as key markets for buy-to-let investors, with new bonds lodged each year increasing by an average of 22.6 per cent.

"This indicates a shift in tenant demand from inner to middle and outer parts of Sydney Metropolitan Area," added Reuveni-Etzioni.