The test, developed by the US Centers for Disease Control and Prevention, will be available to CDC-qualified laboratories this year, the FDA said in a statement Tuesday.
It uses molecular analysis of viral genetic material taken from secretions in a patient's nose and throat to detect and identify commonly circulating human influenza viruses as well as H5N1 viruses and other strains.
The Human Influenza Virus Real-Time RT-PCR Detection and Characterization Panel isolates and amplifies the viral genetic material and labels it with fluorescent molecules, the FDA statement said.
The material is then analyzed by a diagnostic instrument, the Applied Biosystems 7500 Fast Dx, also approved by the FDA Tuesday for use simultaneously with the Flu Panel.
Results can be obtained in just four hours and the system can test multiple samples at once, the FDA said.
"This is a significant achievement for public health surveillance," said Health and Human Services Secretary Mike Leavitt.
"This test allows us to better support laboratories on the front line of influenza testing in the United States and abroad.
"The application of the test to detect an emergent influenza virus would be especially important in the early stages of a pandemic," Leavitt added.
The FDA's chief scientist Frank Torti added: "Because the test can tell the difference between seasonal human influenza viruses and novel viruses, it will also provide qualified laboratories with a means to rapidly detect new influenza viruses that have not been identified yet and that could pose a pandemic risk."
Scientists are concerned that the H5N1 bird flu virus, which currently kills mainly animals, could mutate into a disease that is easily transferable from human to human and spark a global pandemic.
The World Health Organization (WHO) says 243 people have died from bird flu worldwide since 2003, the vast majority of them in Asia.
"H5N1 viruses circulate widely in birds in Asia, Africa and Europe, and have caused human illnesses and death," the FDA statement said.