The Office of Fair Trading is cracking down on sale-and-rent-back companies that promise to rescue homeowners who are struggling with their mortgage repayments.

The watchdog body has asked 16 businesses to back up their advertising claims or face prosecution.

The companies, which market the schemes as a way for homeowners to avoid repossession of their homes, buy properties from people in financial trouble at a significant discount to the market value and then allow the former owners to continue to live in their homes as tenants.

The OFT said that it had asked the companies to justify claims that customers could rent their properties after they were sold at a fair market rate, that they could buy back their homes in future and that rental terms would be flexible.

The Times