WASHINGTON  — Counterterrorism officials said Thursday they are investigating a credible but unconfirmed terror threat involving New York or Washington.

The threat was so specific, and coming at a time of already heightened security just days before the 10th anniversary of the Sept. 11 attacks, that it could not be ignored, a counterterrorism official told The Associated Press. The official requested anonymity to discuss sensitive security information.

Officials would not tell the AP what specifically is being targeted in New York or Washington or the timing of a potential attack. A government official, speaking on condition of anonymity, said raising the terror alert is under consideration.

A law enforcement official in New York, also speaking on condition of anonymity to discuss sensitive security information, described the threat as credible but declined to give details.

Information gleaned from Osama bin Laden’s compound in May indicated that al-Qaida had considered attacking the U.S. on the 10th anniversary and other important dates. Security has been enhanced around the country, including in New York and Washington, in the weeks leading up to Sunday’s anniversary.

President Barack Obama was briefed on the threat information Thursday morning and directed the counterterrorism community to redouble its efforts in response to the credible but unconfirmed information, a White House official said.

“There were very, very specific facts that were made known in this threat,” Rep. Peter King, R-N.Y., told CNN. “I would tell people right now to go about their lives. There’s no need to panic. We don’t know if this threat is real yet. It’s being tracked down.”

White House officials said there were no plans to change Obama’s travel schedule on Sunday in light of the threat. The president is scheduled to mark the 9/11 anniversary with stops at New York’s ground zero, the Pentagon and Shanksville, Pa. He will also deliver remarks Sunday night at a memorial concert at the Kennedy Center in Washington.

“It’s accurate that there is specific, credible but unconfirmed threat information,” Homeland Security Department spokesman Matt Chandler said in a statement. “As we always do before important dates like the anniversary of 9/11, we will undoubtedly get more reporting in the coming days.”

The threat was received late Wednesday night, the counterterrorism official told the AP, and law enforcement has been investigating its validity since. The threat came in a single piece of information and intelligence officials could not determine if it was related to previous intelligence, the official said.

Thursday morning, Homeland Security Secretary Janet Napolitano told reporters that there was “a lot of chatter” around the anniversary of the attacks but that there was no information about a specific threat.