U.S. officials will make a major announcement on Friday as part of their investigation into General Motors' (GM.N) handling of recalled vehicles because of defective ignition switches, the Department of Transportation said in a statement.

The department, along with other U.S. agencies is investigating the timing of the automaker's recall over the faulty switches, which have been linked to at least 13 deaths.

The announcement is expected at 11:15 a.m. EDT (1515 GMT).

GM engineers first discovered the defect in 2001, and the company has been criticized for failing to detect the faulty part and for not recalling the vehicles earlier.

Congress, the Department of Justice, the U.S. Securities and Exchange Commission and several states are conducting their own investigations, and GM has an internal probe that is expected to be completed within the next two weeks.

The announcement Friday comes one day after GM announced a another five recalls covering nearly 3 million vehicles worldwide because of tail lamp malfunctions and potential faulty brakes.