Investors planning to expand their property portfolios are looking to do so with the purchase of complex property types, a specialist in buy-to-let mortgages has said.

In particular, says Mortgages for Business, 28% of those looking to expand said they were considering purchasing houses in multiple occupation, up from just 10% six months ago.

Commercial and semi-commercial property have also piqued the interest of investors.

Those looking to purchase ordinary residential property have fallen slightly to 79% from 83% in November.

David Whittaker, managing director of Mortgages for Business, said that more complex properties offered higher yields, while commercial and semi-commercial property purchases did not incur the Stamp Duty surcharge.

While the proportion of investors looking to expand their portfolio has dipped slightly to 41% from 46% in November 2015, due to forthcoming tax changes and the 3% Stamp Duty surcharge, only 14% plan to shrink their portfolios, down from 18% in November.

Almost a third (30%) said they owned a property via a limited company, up from 22% last year.