NEW YORK (CNN) -- U.S. intelligence and law enforcement agencies have no indications of a terrorist plot against U.S. subway systems, two U.S. law enforcement officials told CNN on Thursday.

The officials were responding to media reports that Iraqi Prime Minister Haider al-Abadi told reporters at the United Nations on Thursday that his country's intelligence agency had uncovered an imminent ISIS plot against New York and Paris subway systems.

A senior administration official told CNN on Thursday that "no one in the U.S. government is aware of such a plot and it was not raised with us in our meetings with Iraqi officials" at the United Nations, including a meeting between al-Abadi, President Barack Obama and Secretary of State John Kerry.

FBI Director James Comey also told reporters that he hadn't heard of the plot.

The Iraqis alerted the United States to the plot, al-Abadi said, according to the media reports.

U.S. agencies are reaching out to Iraq to determine what information it may have, the two officials told CNN.

"We know that our transit and aviation systems are always a target. We know New York is always a target," one U.S. law enforcement official told CNN.

"Do we know what the Iraqi Prime Minister is talking about? No," the official said.

New York Gov. Andrew Cuomo said state officials were treating the report with "utmost precaution" and "coordinating at a high level with local, state and federal partners."

"I want to assure the people of New York that we are monitoring these reports closely and are in close communication with officials in Washington," Cuomo said in a statement.

He said that New York and New Jersey authorities had in recent weeks increased security at mass transit sites and areas as part of a joint security enhancement.

European and New York transit systems have been targeted by terrorists in the past.

On July 7, 2005, 52 people were killed and 700 injured when four bombers planted explosives on three underground trains and a bus in London.

The bombers, from the north of England, used cheap explosives and techniques found on the Internet to carry out the country's worst terror attack.

British intelligence came under criticism after reports that the country had received reliable warnings about such an attack.

Two weeks after the London transit bombings, an attempted second wave of bombings struck other trains and a bus, but the devices failed to explode properly. More than a dozen people were arrested afterward.

Four homemade bombs stuffed into backpacks did not fully explode in the attempt. One person was injured.

In 2012, a Bosnian immigrant accused of plotting to bomb New York's subway system as an "al Qaeda terrorist" was found guilty of conspiracy to use weapons of mass destruction, conspiracy to commit murder, supporting a foreign terrorist organization and other charges.