New York: The FBI and the NYPD seems at be at odds with each other as one claimed that the arrest of "al-Qaeda sympathiser" prevented attacks in the city while the other doubted the "lone wolf's" capability to carry out a terror plot since he seemed "mentally unstable."

The FBI officials were conspicuous by their absence when New York Mayor Michael Bloomberg announced the arrest of "al-Qaeda sympathiser" Jose Pimentel in a late evening press conference on Sunday.

The Federal Investigative Agency was not convinced that the "lone wolf" was a serious threat.

In a press conference, Bloomberg accompanied by Police Commissioner Ray Kelly and District Attorney Cyrus Vance announced that Pimentel planned to carry out terror attacks in the city targetting police officials and military personnel returning from Iraq and Afghanistan.

However, the officials from the Federal Bureau of Investigation were not present in the news conference.

Kelly explained that while FBI was "fully informed" about the case, the New York Police Department (NYPD) and the District Attorney's office had to "act quickly" and make the arrest as 27-year-old Pimentel was close to finishing making pipe bombs.

A law enforcement official told PTI that "FBI chose not to take on the case and it was decided that Pimentel's arrest would be made at the state level."

The FBI was doubtful over whether Pimentel would be capable of carrying out a terror plot on his own as they believed him to be mentally unstable, the official said.

An FBI official, speaking on condition of anonymity, said Pimentel was "NYPD's intelligence case and FBI need not interfere in the case."

Terrorism cases are generally handled by federal authorities. Another FBI personnel from the agency's New York office said the Joint Terrorism Task Force was consulted regarding the New York Police investigation of Pimentel.

The JTTF itself includes the NYPD and FBI and about 50 other law enforcement agencies charged with taking action against terrorism.

"The JTTF was consulted in the case and then it was decided by those in the decision making process to take the case to the Manhattan district attorney," the FBI official said.

He said FBI always cooperates with other units in terrorism-related cases.

Kelly said the federal authorities were fully informed about Pimentel, who was under police surveillance since 2009.

Bloomberg described Pimentel as a "lone wolf" who was inspired by "al Qaeda propaganda" and was not part of a larger conspiracy emanating from abroad.

Pimentel, an unemployed native of the Dominican Republican, is a US citizen.

Meanwhile, The New York Times quoted Pimentel's mother Carmen Sosa as saying that she was "sorry about my son."

"My son is not a terrorist, my son was like an normal boy, like a normal guy."

"He likes the way of the Muslims," she said, explaining that he had converted from Roman Catholicism.