The lender said that with immediate effect its broker support phone lines and broker chat are no longer available until further notice.
It emphasised that procuration fee payments will be unaffected.
A Nationwide spokesman said: “As a direct result of the latest government advice around coronavirus, we have taken the decision to close our dedicated broker support lines until further notice.
“We continue to work hard to progress all ongoing applications across both Nationwide and The Mortgage Works (TMW). In the first instance, we encourage brokers to use our online services, where they are able to track cases for both Nationwide and TMW, as well as find product criteria and payment holiday information.
“However, local business development managers (BDMs) remain available to support where necessary. Brokers will also continue to see procuration fees paid as normal and on time via their nominated corporate account.”
It added: “We thank brokers for their patience as we know this is an extremely challenging time for everyone.”