Global credit turmoil has spilled over into the market for bonds backed by US commercial mortgages, threatening to push down property prices and scuttle deals.

Issuance of US commercial-mortgage-backed securities fell to $6.3bn in October, down 84 per cent from a record $38.5bn in March, according to Commercial Mortgage Alert, a trade publication. The decline in CMBS issuance is crucial because such securities have provided an estimated 40 to 60 per cent of financing for new commercial property purchases in recent years.