Ludlow Thompson says schemes launched in Turkey, Bulgaria and Dubai have been heavily advertised in the UK, offering guaranteed rents for one or two years.
While the guaranteed rents look attractive, they often bear no relation to what investors could charge tenants. Once the guaranteed period comes to an end, investors may not be able to get anywhere near the guaranteed rent, or even be sure they will be able to find tenants.
In one scheme identified by Ludlow Thompson, a Turkish investment company is offering a 40 per cent return over two years on a newly built development. In many cases, developers are leaving guaranteed rental properties unlet - or letting them out at much lower returns.
Stephen Ludlow, the agent's director, said: "If there is no rental demand for the property, the investor could see their yield fall off a cliff once the guarantee runs out."
The warning follows growing concern about a bubble in the buy-to-let market. Pension advisers are worried that many investors had put cash into their plans in to invest in buy-to-let following changes to the law last April. These changes were scrapped in December.
Although guaranteed return schemes look attractive, investors can end up worse off over the longer term, if they get stuck with low-yielding property that proves difficult to sell.
"A lot of investors have bought new-build flats in the UK on guaranteed rents and been disappointed with rental performance once the guarantee has expired," Ludlow warned.
"But at least in the UK, most of these schemes are being marketed in large metropolitan areas with an active and researchable lettings market."
Investors losing out on guaranteed rental schemes are unlikely to be able to claim compensation.
The Financial Services Authority, Britain's chief City regulator, has repeatedly warned property investors to take care in the buy-to-let market. Property developers and buy-to-let mortgage products are not regulated by the watchdog.
Overseas schemes are likely to be particularly difficult for investors to complain about. However, the popularity of buy-to-let investment property abroad has risen over the past 12 months, following a decline in the rental yields on British property.
Last month, the Mortgage Works, the buy-to-let lending arm of the Portman Building Society, said that it would stop offering mortgages on newly built flats in the UK, because it had concerns about the true value of many of these housing developments.Reuse content