(Reuters) - The U.S. Food and Drug Administration said on Monday it had taken steps to strengthen the data requirements for surgical mesh devices when used to repair pelvic organ prolapse (POP) via the vagina.

POP occurs when the muscles and tissue of the pelvic floor become stretched, torn or weakened and can no longer support pelvic organs, leading to their prolapse into the vagina.

Over the past several years, the FDA has received thousands of reports of complications, including bleeding, organ perforation and urinary problems, involving the use of mesh for transvaginal POP repair, the agency said.

These devices have been used by surgeons since the 1950's to repair abdominal hernias. In the 1970s, gynecologists began implanting surgical mesh for the abdominal repair of POP and, in the 1990's, for the transvaginal repair of POP.

The FDA noted that an advisory panel of experts in 2011 recommended that more data was needed to establish their safety.

Boston Scientific Corp is among a handful of manufacturers that have collectively faced an estimated 100,000 lawsuits in state and federal courts over transvaginal mesh, alleging that poor design and substandard materials can cause side effects such as bleeding, infection and nerve damage.

Other major defendants include Johnson & Johnson's Ethicon unit and C.R. Bard.

The FDA on Monday issued an order to reclassify these medical devices from class II or moderate-risk devices, to class III, which encompasses high-risk devices. (http://1.usa.gov/1MPbStj)

In addition, the agency now also requires manufacturers to submit an application to support the safety and effectiveness of the surgical mesh, particularly for POP. These orders do not apply other indications, like stress urinary incontinence or abdominal repair of POP.

Manufacturers of already available surgical mesh used to treat POP transvaginally will have 30 months to submit an application for their devices. Makers of new devices must submit their application before they can be approved for marketing, the FDA said.

(Reporting by Natalie Grover in Bengaluru; Editing by Maju Samuel)