Embattled blood-testing services provider Theranos Inc. has confirmed that it has decided to shut down its blood-testing facilities and slash its workforce by more than 40 per cent.

In a letter posted to its official website on Wednesday, Theranos said that it would close its lab operations, shut down its wellness centers and lay off nearly 340 employees.

Elizabeth Holmes, the founder and chief executive officer of Theranos, said that the company decided to shut down its blood-testing facilities so that it could focus on an initiative to create small medical testing machines.

Theranos has been under intense scrutiny from federal regulators, including the Food & Drug Administration (FDA). The company’s blood-testing facilities also suffered some severe sanctions, including the one that banned Ms. Holmes from owning and operating a medical lab for two years.

Without addressing the status of various federal probes, Ms. Holmes attempted to address concerns that the company was overly secretive about its technology. She said, “We have a new executive team leading our work toward obtaining F.D.A. clearances, building commercial partnerships and pursuing publications in scientific journals.”

Ms. Holmes, a self-made billionaire, founded Theranos when she was just 19 years old. Her venture successfully persuaded a number of high-profile Silicon Valley investors, growing to a market value of an astounding $9 billion.