An ex-cop busted in a nationwide kiddie porn roundup pleaded guilty yesterday in Brooklyn Federal Court.

Brian Mathews admitted using his Web TV box to access an Internet site to look at child pornography.

"I just viewed them, I did not download them," Mathews told federal Judge Carol Amon.

Brooklyn Assistant U.S. Attorney Katya Jestin said the pornography depicted "an infant engaged in sexually explicit content."

Mathews, 40, a former Patrolmen's Benevolent Association delegate, faces up to five years in prison and a $250,000 fine when he is sentenced.

He was fired from the NYPD in 1998 after he was found guilty at an administrative trial of ordering child porn through the mail.

The ex-cop was among 26 people arrested in the metropolitan area in March as part of a nationwide probe dubbed Operation Candyman. One of the Web sites targeted by the feds was called "thecandyman" and billed itself "for people who love kids."