A consumer watchdog group scolded the Food and Drug Administration Thursday for taking weeks to evaluate the latest problem with Baxter's drug pumps, which have been plagued by safety issues for years.

In January, Baxter International sent a warning to customers about issues with its Colleague infusion pumps that could cause them to stop pumping and overheat. On Wednesday the company said the FDA classified the announcement as a Class I recall, its most severe warning. The classification applies to problems that can cause "serious adverse health consequences or death."

Public Citizen's Dr. Sidney Wolfe blasted the agency in a letter Thursday for not moving faster.

"Why did it take the FDA 47 days, almost 7 weeks ... to decide that this problem was serious enough to merit being classified as a Class I recall?" Wolfe wrote in a letter to acting FDA Commissioner Dr. Frank Torti.

FDA's classification has limited real-world impact. Baxter's products are not actually being called off the market, but the serious warning is necessary because malfunctions with the devices can be fatal.