Where new instructions are concerned, London has reported a rise during recent months, most notably in July and August.
NI recorded the strongest growth across the United Kingdom for house prices, with respondents also more upbeat on the outlook, RICS said.
The balance also fell further into negative territory in the South East of England.
The Royal Institute of Chartered Surveyors (RICS) found a slight increase in the percentage of surveyors reporting a fall in prices in the organisation's August residential market survey.
Showing the lowest reading in 9 years, London's price gauge continued to be negative, whilst the South East price indicator also weakened for the third consecutive month.
Buyer enquiries remained flat for the ninth straight month, while 4 per cent more respondents saw a fall in new sales instructions.
"The latest results continue to suggest that the greatest pressure on both prices and activity continues to be felt in prime central London market", said Simon Rubinsohn, chief economist at the RICS.
However surveyors said anecdotal evidence suggests there is a divergence between the upper and lowers ends of the market, with a stronger picture below £250,000.
Rental prices will drive upwards as 61% of surveyors expect a flurry of landlords to exit the market in the next 12 months, according to the RICS August survey.
London's prime central districts have borne much of the brunt of the slowdown, in part reflecting concerns about the impact of Brexit on the capital's financial services industry and other related sectors. Just over half of its members believe that this will remain the case over the next three years. Moreover, for the next three years, 52% felt there would be a net reduction in landlords, with only 17% suggesting a rise. Although the Build to Rent offer is now stepping up a gear, there clearly is some doubt as to whether it can do so at a fast enough pace to address the shortfall which may result from the more hostile environment for buy to let investors, ' he added.
Although signaling a return to growth, this measure is consistent with only a marginal rise in national prices, RICS said. The sector is extremely diverse, including many one home landlords, ' he pointed out.
The cost of privately renting a home in the United Kingdom is set to increase as landlords pull out of the sector in the coming year, surveyors have warned.