General Motors recalled about 780,000 sports utility vehicles in North America on Friday over faulty rear power liftgates which can fall suddenly and cause injuries.

The recall affects 2008-2012 Buick Enclaves, 2009-2012 Chevrolet Traverses, 2007-2012 GMC Acadias, and 2007-2010 Saturn Outlooks.

GM said the gas struts which hold up the liftgates "may prematurely wear", making them unable to support the liftgate's weight.

GM said 56 people have been injured because of the problem.

The SUV liftgate recall came two days after GM recalled nearly 200,000 Hummer SUVs worldwide for an electrical problem which has resulted in dozens of fires.

GM is still working to resolve the problems of some 30 million vehicles recalled over the past two years, most of them for a ignition-switch malfunction that resulted in at least 121 accident-related deaths.