Falling house prices and record low interest rates have doubled the number of buy-to-let landlords who are increasing their property portfolios.

According to the Association of Residential Letting Agents (ARLA), higher yields and lower mortgages make bricks and mortar more attractive than rock-bottom returns on savings accounts.

However, a glut of "accidental landlords" - those who cannot sell during the housing market downturn - is forcing down rents as supply continues to outstrip demand.

This means the average monthly rent on a house has fallen to £1,570 from £1,682 during the previous three months, with a flat now at £987 compared with £1,013.

Nevertheless, lower house prices have increased yields to 5.1%, up from 4.8% during the first three months of the year, with annual rents representing 5% of a flat's value, up from 4.9%.

As a result, 16% of letting agents report that buy-to-let landlords increased their portfolios during the second quarter of the year, compared with 8% during the first three months.

Much of the increase is being driven by the dramatic falls in the Bank of England base rate seen between October and March.

Said ARLA spokesman Ian Potter: "Each quarter we glimpse a bit more activity as the bargains get snapped up and confidence is restored in buy-to-let as a viable long-term investment vehicle, particularly if the returns are rising too."

The organisation reports on its website that "not since the golden age of the Edwardians, when 90% of all housing was rented, has the private rented sector looked so attractive to private investors.

"The market may only stand at some 11%, after dropping to an all time low of just 7% in 1989, but real growth has been achieved since then, and is forecast to continue."

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