The rate at which rents are falling has accelerated as the letting market continues to suffer from an oversupply of properties, research showed today.

A record 55% more chartered surveyors in Great Britain reported falling rents rather than rising ones during the three months to the end of April, the Royal Institution of Chartered Surveyors said.

The figure was the highest level since the survey began in 1999 and up from 48% more surveyors who reported declining rents during the previous quarter.

Surveyors also reported the first drop in property yields, which measures rental income as a percentage of a property's value, since April 2007, suggesting rents are now dropping at a faster rate than house prices.

But despite the gloomy figures, surveyors are more upbeat about the future for the market, with many predicting a slowing in the rate at which rents are falling as the housing market picks up and frustrated sellers put their homes on the market again, reducing the current problem of oversupply.

A balance of 25% of surveyors expect rents to fall during the coming months, nearly half the 41% who predicted further falls during the previous three months.

There was also a slowdown in the rate at which new rental properties came on to the market during the quarter, with 17% more surveyors reporting a rise in rental flats, and 12% more seeing an increase in houses, well down on the jumps of 44% and 49% respectively reported during the three months to the end of January.

The pick-up in the housing market also appears to have increased the likelihood that landlords will consider selling their property when their current tenancy expires, with this rising to 1.8% up from just 0.2% during the previous quarter.

Tenant demand for rental property continued to increase during the three months to the end of April, but at a slightly slower pace as buyers returned to the housing market.

A balance of 16% more surveyors reported a rise in new lettings during the period, down from 42% in the three months to January.

RICS spokesperson Jeremy Leaf said: "Property transactions are starting to rise from very low levels and the influx of supply in the rental market has slowed as vendors begin to find buyers.

"Demand for rental property is still high but tenants have been able to take advantage of a flooded market to negotiate lower deals.

"Even so, the downward pressure on rents should ease in the coming months providing some good news for landlords."

The rental markets are weakest in London and Scotland, with 85% more surveyors reporting a fall in rents for houses in the capital than a rise, while 80% more surveyors in Scotland reported falling rents for both houses and flats, up from 58% during the previous quarter.