The US congressional committee has said that it is investigating General Motors' recall of nearly 1.6 million vehicles over faulty ignition switches.The problem could turn off the engine in affected vehicles while they were being driven, disabling the airbags. The car maker announced the recall last month, but it has admitted employees knew about the defect as early as 2004. The issue has been linked to 13 deaths and GM has also launched an internal investigation into the matter. Meanwhile, a recent report claimed that the US safety regulator had received more than 260 complaints over the past 11 years about GM vehicles that "suddenly turned off" while being driven. But they declined to investigate the problem, the report alleged.