By Rich McKay

The United States will conduct a test of its emergency warning system on Wednesday, sending alerts across cellphones, radio and television to millions of Americans.

The Federal Emergency Management Agency (FEMA) and the Federal Communications Commission (FCC) are running the test to ensure the warning system functions properly.

Alerts will begin at 2:20 p.m. ET (1820 GMT) with a text message to cellphones reading, "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed." Messages will be displayed in English or Spanish, depending on the device's language settings.

Separate alerts will be broadcast across television and radio and last about one minute.

It will be the seventh such test of the emergency alert system, FEMA said in a statement. Its purpose "is to ensure that the systems continue to be an effective means of warning the public about emergencies," it added.

Russia also tested its emergency public warning systems on Wednesday, blaring out sirens and interrupting some television and radio broadcasts.

(Reporting by Rich McKay in Atlanta; editing by Rami Ayyub)