The lender, which allows brokers to reserve products by securing funding online, says it has received high demand recently because other lenders have repriced upwards, making its products more competitive.
In order to manage demand, it has reduced the tranches available to brokers for a temporary period.
Mortgage Strategy understands brokers have been struggling to secure funds in recent days.
A spokeswoman for Woolwich says: “We are currently receiving huge demand for our products and have therefore decided to reduce our tranches for a few days to manage this demand.
“We have no current plans to increase the rates on our products.”