European regulators are launching a new probe into the safety of GlaxoSmithKline Plc's diabetes pill Avandia, adding to pressure on a medicine that already faces a grilling from U.S. experts next week.

The European Medicines Agency (EMA) said on Friday its decision to review the risks and benefits of the drug followed the publication of fresh studies questioning the cardiovascular safety of the drug.

Experts from the agency's Committee for Medicinal Products for Human Use (CHMP), who last reviewed the product in early 2010, will discuss the issue at their next plenary meeting in London on July 19-22.

Avandia, known generically as rosiglitazone, is currently authorized for sale in Europe on its own, in combination with metformin as Avandamet and with glimepiride as Avaglim.

Once all relevant data on the benefits and the risks of rosiglitazone have been looked at, the CHMP will issue an opinion on whether or not the marketing authorizations for these medicines should be revoked, suspended or changed, the EMA said in a statement.

Shares in Glaxo fell 1.9 percent following the news by 0920 GMT (520 a.m. EDT), underperforming a little-changed European drugs sector.

Avandia was once Glaxo's second-biggest drug but its sales have plunged since a safety controversy first erupted three years ago.

Glaxo has vigorously defended the drug and Tony Hoos, Glaxo's European medical director, said on Friday that Avandia was an important treatment option for appropriate Type 2 diabetes patients.

Concerns about the medicine's adverse impact on the heart have triggered a slew of lawsuits in the United States and a U.S. Food and Drug Administration advisory panel will meet on July 13-14 to help decide Avandia's future in the country.

(Reporting by Ben Hirschler; Editing by Erica Billingham)