NEW YORK, 5 MAR, 2010: An imam accused of tipping off al Qaeda-trained militant Najibullah Zazi as he plotted to set off bombs in New York's subway system pleaded guilty on Thursday to lying to the FBI about his contact with Zazi, Reuters reported.

Ahmad Afzali, 38, an Afghan citizen, made the plea in Brooklyn federal court in a deal with prosecutors. The agreement saw him plead guilty to charges of lying and eliminated the more serious charge of obstructing a terrorism investigation.

"On September 11 (2009), I called Najibullah Zazi. ... During that conversation, I told Najibullah that law enforcement authorities had been to see me about him," Afzali, wearing a light gray suit, told the court in emotional remarks where he cried repeatedly.

Afzali was arrested in September as part of a probe into what Attorney General Eric Holder called one of the most serious security threats to the United States since the September 11 attacks in 2001.

"It was in motion. And it would have been deadly," Holder has said.

Afzali said: "When I was asked (by the FBI) whether I had told Zazi about law enforcement being interested in him, I lied and said I did not. My intention was not to protect Zazi but to protect myself."

"In doing so, I failed to live up to my obligation to this country, my community, my family, and my religion. I am truly sorry," he said.

Afzali faces up to six months in prison when sentenced, set for April 8. Under the deal, he must leave the country within 90 days of finishing his sentence.

Afzali pleaded not guilty to the charges of obstructing a terrorism investigation in November.

In what was hailed as a political victory for Holder, Zazi pleaded guilty in February to conspiracy to use weapons of mass destruction, conspiracy to commit murder in a foreign country and providing material support to al Qaeda.

Zazi moved to the New York City borough of Queens as a teenager and went to school there. He attended a mosque led by Afzali, a self-proclaimed pro-American imam who cooperated with police in previous investigations.

Asked about Zazi, Afzali alerted him he was under scrutiny, which forced authorities to bring Zazi in for questioning sooner than planned. Afzali lied about the tip-off when questioned by the FBI, prosecutors said.