Washington (CNN) -- The federal government said it will recommend that new cars have rear-view video systems, a move immediately denounced as "insufficient" by safety groups who say the cameras should be mandatory. 

The camera and monitor system enables drivers to see whether people or objects are in the blind spot behind vehicles. 

The National Highway Traffic Safety Administration said Tuesday it will add the rear-view video systems to its list of recommended features under its New Car Assessment Program, designed to encourage car manufacturers to improve vehicle safety. 

But safety groups called the action a stalling tactic, saying the agency is dragging its feet in fulfilling a congressionally imposed deadline to issue a rule on rear visibility. 

Passed in 2008, the law had a 2011 deadline. The regulation is now two and a half years overdue. 

Death toll from backover accidents grows 

The NHTSA action "is an inadequate substitute for issuing a mandatory safety regulation," Jackie Gillan, president of Advocates for Highway and Auto Safety, said in a statement. "In fact, safety advocates are concerned that NHTSA's announcement is an attempt to divert attention from their failure to act." 

The NHTSA announcement Tuesday came just one day before a group of safety advocates, including two parents who unintentionally hit their children while backing up, was expected to file suit against the U.S. Department of Transportation, which includes NHTSA. 

The suit is to be filed Wednesday morning by Greg Gulbransen, who reportedly backed over his 2-year-old son, Cameron, in his driveway in 2002, killing him, and by Susan Auriemma, who backed over her 3-year-old daughter, Kate, in her driveway in 2005, injuring her. 
What does it do?
 designed to encourage car manufacturers to improve vehicle safety. 