CHARLOTTE, N.C. - FBI agents searched the North Carolina house of Paula Broadwell on Monday, signaling renewed activity in the investigation that revealed her extramarital affair with CIA Director David Petraeus that led to his resignation.

A combination photo shows Jill Kelley (L), a friend of former US General David Petraeus' family, in Tampa, Florida on Nov 12, 2012 and Petraeus' biographer Paula Broadwell, in an ISAF handout image, originally posted July 13, 2011. [Photo/Agencies]

Agents entered the house in Charlotte, North Carolina, carrying boxes around 9:00 pm (0200 GMT Tuesday) and were still there almost two hours later.

U.S. officials had said in recent days that their investigation in the Petraeus affair was largely complete and that prosecutors had determined it was unlikely they would bring charges in the case, which started as suspected cyber-harassment involving Broadwell and Jill Kelley, a Petraeus friend.

Lawmakers and others have questioned whether Broadwell, who co-wrote a biography of the decorated former general, obtained classified information from him or another source.

There was no sign that Broadwell or members of her family were at the house during the FBI search.

Shelley Lynch, a spokeswoman for the FBI in Charlotte, confirmed that agents were at the house but declined further comment.