However, they expressed concern at the volume of "terrorist" threats at home and overseas on the eve of the busy holiday period
The Federal Bureau of Investigation (FBI) said there was no truth in an ABC news report of "credible" information pointing to a possible strike against New York City, site of the September 11 attacks.
"We are not aware of any credible imminent threat to New York City," said Jim Margolin, an FBI spokesman there. "We are not currently running down anything we would characterise as a credible imminent threat."
New York City is on heightened
alert since September 11 attacks
A White House spokesman in Washington said warnings had been sent to security personnel around the country urging extra vigilance during the holiday season.
The spokesman Scott McClellan, told reporters he had seen a news report on the threat but added: "I'm not in a position to confirm anything about it. You know, we just say that we have remained concerned about the volume of reporting of threats."
The Jewish festival of Hanukkah begins on Friday night, Christmas falls next Thursday and preparations are under way for New Year celebrations.
Earlier, ABC television reported that US intelligence intercepts in the past 48 hours suggested an increase in threats to a number of US cities, including New York City, Los Angeles and Washington.
To this, a New York Police Department spokesman, Michael O'Looney, said in a statement the department "has no credible intelligence pointing to a specific or imminent terrorist threat to New York City."
"You know, we just say that we have remained concerned about the volume of reporting of threats"
spokesman, White House
But ABC quoted its sources as saying the threat to New York involved a human bomber, possibly a female, although no specific target had been identified.
New York City has remained on a heightened level of alert since the September 11 attacks. The US is on an "elevated" status of alert, the third on a five level scale.
ABC said the information was coming from a number of sources including intelligence intercepts and US interrogation of recent detainees.
Discussions between local and federal law enforcement officials are currently under way to develop a response, the network added.