WASHINGTON (AP)  -- The Justice Department and New York Police Department are feuding over surveillance of suspected terrorists -- and how quickly it can be legally approved.

In a testy letter NYPD Commissioner Ray Kelly accused the Justice Department of putting New Yorkers at risk by dragging its feet on approving paperwork for eavesdropping warrants.

``Consequently, the federal government is doing less than it is lawfully entitled to do to protect New York, and the city is less safe as a result,'' Kelly wrote in an Oct. 27 letter to Attorney General Michael Mukasey.

Mukasey shot back four days later, on Oct. 31, raising concerns that Kelly's cops were asking for extraordinary surveillance powers outside legal boundaries.

``In effect, what you ask is that we disregard FISA's legal requirements, which are rooted in the constitution,'' Mukasey wrote Kelly. ``Not only would your approach violate the law, it would also in short order make New York City and the rest of the country less safe.''

The letters were obtained Wednesday by The Associated Press.

At issue is the legal process police and prosecutors must go through in applying for wiretaps or other surveillance methods on foreign terrorist suspects.

The federal Foreign Intelligence Surveillance Act, or FISA, requires investigators to obtain a warrant from a secret court in Washington to eavesdrop on suspected terrorists inside the country.

Generally the FBI or other federal investigators apply for the warrants, which must be reviewed by the Justice Department before they are submitted to the FISA Court for final approval. But in recent years, the NYPD has ramped up its own counterterror mission, and is allowed to apply for the warrants as part of a task force with other local and federal agencies.

Last year the FISA Court approved 2,371 warrants targeting people in the United States believed to be linked to international terror organizations. It denied three warrant applications in full and partially denied one, according to Justice data. Additionally, the court sent 86 applicants back to the government for changes before approving them.

It was unclear Wednesday how many of the warrant applications were from the NYPD.

One official familiar with the situation said the Justice Department has not rejected any of the NYPD's applications.

But, several intelligence officials said, Kelly has grown frustrated with questions from Justice about whether the NYPD was overstepping legal boundaries related to whether it had enough probable cause to ask for the extraordinary surveillance measures.

All of the officials spoke on condition of anonymity because they were not authorized to discuss the situation publicly.

In conversations with Washington, the officials said, Kelly cited ``several'' terrorism cases where the Justice Department's questions slowed warrants from being approved, which ultimately put New York at risk. The outcome of those cases was not immediately clear.