House prices in the UK continued to rise in September even though interest from buyers was at its lowest level since last summer's EU referendum, according to a report.

The Royal Institution of Chartered Surveyors (Rics) said its house price balance was unchanged at +6, indicating a marginal increase in prices during the month.

This was despite 20% more surveyors reporting a fall rather than rise in demand from would-be buyers – the sixth straight month of negative reading and the weakest figure since July 2016.

Rics chief economist Simon Rubinsohn attributed the continued increase in house prices to a lack of supply in the market, with average stock levels on estate agents' books stuck near record-low levels at 43.3 during September.

"We are continuing to see evidence of shortage of stock both in the new build and second-hand market," he said.

"Against such a backdrop, prices in general are likely to remain elevated and indeed, as the survey indicates, continue to rise over the medium term in most parts of the country."

Some 15% more survey respondents reported a fall in sales volumes during September – the lowest reading since July 2016 – with Rics suggesting expectations of an interest rate rise from the Bank of England were contributing to a more cautious tone in market sentiment.

The report also found a disparity in house price growth between London and the south east of England – where prices fell in September – compared to the rest of the country, where prices are mostly on an upward trend.

"In part, this is a reflection of affordability constraints hitting the higher priced segments of the market," Rubinsohn said.

"It is perhaps also indicative of a shift in economic momentum in the face of the increasing possibility of the first hike in base rates in over ten years."

Data released by Halifax last week showed a 4% gain in UK house prices in the three months to September, the highest rate of growth recorded since February.