Iraq's prime minister said Thursday that captive Islamic State militants told his intelligence agents of an alleged plot to attack subways in the United States and Paris.
A senior Obama administration official said no one in the U.S. government is aware of such a plot, adding that the claim was never brought up in meetings with Iraqi officials this week in New York.
President Barack Obama met with al-Abadi Wednesday.
The administration official was not authorized to discuss the matter publicly by name and spoke on condition of anonymity.
There was no immediate comment from France. A half-dozen French officials contacted by The Associated Press said they knew of no plot.
Prime Minister Haidar al-Abadi said he was told of the purported plot by officials in Baghdad, and that it was the work of foreign fighters who had joined the Islamic State group in Iraqi, including French and U.S. nationals.
Asked if the attacks were imminent, he said, "I'm not sure." Asked if the attacks had been thwarted, he said, "No, it has not been disrupted yet... this is a network."
"Today, while I'm here I'm receiving accurate reports from Baghdad that there were arrests of a few elements and there were networks from inside Iraq to have attacks ... on metros of Paris and U.S.," al-Abadi said, speaking in English. "They are not Iraqis. Some of them are French, some of them are Americans. But they are in Iraq."
He made the remarks at a meeting with journalists on the sidelines of a gathering of world leaders at the United Nations General Assembly. The Iraqi leader told journalists Thursday that the plot was the work of foreign fighters of the Islamic State group in Iraq.
Al-Abadi declined to give the location in the U.S. where the such an attack might occur.
The Islamic State extremists' blitz in Iraq and Syria prompted the United State to launch airstrikes in Iraq last month, to aid Kurdish forces who were battling the militants and to protect religious minorities.
In addition to the brutality Islamic State has visited on the people in Iraq and Syria, western leaders have voiced concern that the group would move its terror operations outside the region.
This week, the U.S. and five allied Arab states expanded the aerial campaign into Syria, where the militant group is battling President Bashar Assad's forces as well as Western-backed rebels.
Western leaders have voiced concern that the Islamic State group would move its terror operations outside the Middle East.
John Miller, the New York Police Department's top counterterror official, said they were aware of the Iraqi official's statements "and we are in close contact with the FBI and other federal partners as we assess this particular threat stream."
New York is the home to the country's largest subway system.