(Reuters) - Walgreens Boots Alliance Inc (WBA.O), the largest U.S. drugstore chain, threatened to terminate its relationship with Theranos Inc unless the blood-testing company quickly fixes the problems found by federal inspectors at its laboratory in California, the Wall Street Journal reported.
The drugstore chain gave the warning in a letter to Theranos late last month, the Journal said, citing people familiar with the matter.
A spokesman for Walgreens declined to comment.
Walgreen had suspended laboratory services by Theranos on Jan. 28 after the U.S. Centers for Medicare & Medicaid Services said that Theranos' deficient practices at its Newark lab posed "immediate jeopardy to patient health and safety".
Theranos has been in the spotlight after reports in the Wall Street Journal suggested that its blood-testing devices were flawed and had problems with accuracy.
The 40 Theranos "wellness centers" at Walgreens stores in Arizona are the primary source of revenue for the blood-testing company and its conduit to consumers, the newspaper said.
Theranos was unavailable for comment outside regular U.S. business hours.
Reporting by Parikshit Mishra in Bengaluru; Editing by Gopakumar Warrier