(Adds press conference planned, details, background)

By Zachary Fagenson

MIAMI, Oct 26 (Reuters) - Federal authorities arrested a person on Friday in connection with at least a dozen parcel bombs sent this week to Democratic politicians and high-profile critics of U.S. President Donald Trump, the U.S. Justice Department said.

The person was taken into custody in the Miami area, a U.S. law enforcement official said. The investigation into this week's wave of suspicious packages focused on southern Florida and a mail sorting facility in the area.

The U.S. Justice Department will hold a news conference at 2:30 p.m. EDT. (1830 GMT), a department spokeswoman said.

Citing an unnamed source, cable network MSNBC said the suspect was a man in his 50s. CNN said the arrest was made in Plantation, a city near Ft. Lauderdale, Florida. Reuters could not immediately confirm those reports.

No one claimed responsibility for parcel bombs, which were denounced by authorities as terrorism, and came less than two weeks ahead of U.S. congressional elections that could alter the balance of power in Washington.

Police found two of the suspicious packages on Friday addressed to U.S. Senator Cory Booker and James Clapper, the former U.S. director of national intelligence, officials said.

The 11th package was addressed to Booker, a Democratic senator from New Jersey, and was discovered at a mail sorting facility in Florida, the FBI said. A 12th package was addressed to Clapper at cable network CNN and was intercepted at a New York City post office, a federal law enforcement official said.

(Reporting by Zachary Fagenson; Additional reporting by Gina Cherelus, Gabriella Borter and Peter Szekely in New York, Mark Hosenball, Makini Brice and Susan Heavey in Washington, and Brendan O'Brien in Milwaukee; Writing by Daniel Wallis; Editing by Lisa Shumaker and Jeffrey Benkoe)

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