The value of commercial property loans in breach of their agreed terms more than trebled in six months as rapidly falling real estate prices hit a heavily leveraged sector struggling under almost £208bn of debt.

With more than £76bn of debt needing to be refinanced before the end of 2010 and increasing numbers of loans slipping into default, the findings of an influential survey of property lending, to be published on Wednesday, will add to warnings that commercial property could be a timebomb for banks that supported the real estate boom.