Buy-to-let mortgages now represent a significant part of financial advisers' business, according to a new report.
Research by Mortgage Trust found that advisers now believe that such mortgages make up 21 per cent of their business.
John Heron, managing director of the firm, said: "Buy-to-let is the biggest niche sector in the UK mortgage market and our research shows that it is continuing to grow."
Landlords continue to purchase new properties having enjoyed a greater level of tenant demand and higher rental incomes, Mr Heron remarked.
Buy-to-let remains a "popular" option for investors and is generally "risk averse" market, he added.
Paragon Mortgages recently reported that 46 per cent of the landlords it surveyed said they believed that achievable rent levels had risen over the last six months.
The firm found that a further 51 per cent believed that rents had remained stable.
However, Paragon argued that landlords may have been put off purchasing more properties until the cost of borrowing becomes more affordable.