A suspect in a plot to disguise himself as a Jew and unleash a bloodbath in Manhattan synagogues and churches pleaded guilty to terror charges Tuesday, Dec 4, and will be sentenced next month, authorities said, according to AFP.

The guilty plea by Ahmed Ferhani, 27, "marks the first time a terrorist has been convicted on state terror charges since the New York Anti-Terror Laws were passed shortly after Sept 11, 2001," Manhattan District Attorney Cyrus Vance said in a statement.

The Algerian native is set to be sentenced Jan 30.

Ferhani was arrested in May 2011 with Moroccan native Mohamed Mamdouh, 21. The pair was also alleged to have said they would attack the Empire State Building.

Documents presented in their cases said the two conspired between October 2010 and May 2011 to plant bombs in Manhattan churches and synagogues to send a violent message to U.S. Christians and Jews.

At the time of their arrest, New York Mayor Michael Bloomberg said there had been 13 plots against New York since nearly 3,000 people were killed on 9/11 at the World Trade Center in Manhattan, the Pentagon and in Shanksville, Pennsylvania.

According to the Manhattan prosecutor's office, the undercover investigation lasted seven months, during which time Ferhani and Mamdouh were recorded making plans for attacks against the city's large Jewish population.

New York, targeted repeatedly by bombers over the last two decades, has been on heightened alert since U.S. commandos killed Al-Qaeda leader Osama bin Laden in Pakistan.