A staggering 65 per cent of buy-to-let purchases over the last year were made by cash buyers according to the latest rental market index from estate agents Countrywide.

In the past 12 months this accounted for £21 billion in cash sales.

Johnny Morris, Countrywide's research director, said: “Landlords have increased their housing wealth considerably over the last ten years. This means cash purchases are steadily becoming a bigger part of the market.

"But a landlord buying with cash will often have a mortgage either on their personal home or other properties in their portfolio.

"Rising prices have allowed landlords to take equity out of both their personal or other rental homes to expand their portfolios."

The proportion of landlords buying in cash has steadily increased over recent years.

The total amount of cash spent is £200 million more than last year and a third higher than in 2007 when Countrywide started monitoring the market.

Northern and Scottish landlords are the most likely to buy with cash.

Nearly 80 per cent of buy-to-let property purchases in the North East are for cash, followed by Scotland at 71 per cent.

Meanwhile in London, landlords are much more dependent on debt to buy their next rental property – only 42 per cent of purchases there are cash deals.

In 2007 mortgaged-backed purchases were twice that of cash sales, but now the situation has been reversed.

Over the past 12 months buy-to-let purchases made with a loan amounted to £13.3 million while cash sales amounted to £21 million.