It is not clear how long the monitoring of phone calls has been authorized, but NBC News said it learned that it was in place in the weeks leading up to the April 9 raids on Cohen's office, hotel room and home.

Cohen is under criminal investigation by prosecutors from the U.S. Attorney's Office for the Southern District of New York for issues that include his business dealings.

In addition to serving as Trump's lawyer, Cohen was also counsel for the Trump Organization, the business entity the president previously ran.

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