American Airlines Flight 109, a Boeing 777, left London at 5:55 a.m. EDT headed for Boston, said Tim Wagner, a spokesman for the Fort Worth, Texas-based airline.
"The flight returned to Heathrow due to a security issue that needed to be resolved in London," he said. "It was not a security threat to the aircraft. The flight was in no danger."
Wagner provided no other details.
Phil Orlandella, a spokesman for the Massachusetts Port Authority, which runs Boston's Logan Airport, said staff were told at a meeting Monday morning that the name of a passenger on the flight matched one on the no-fly list. He had no further information.
"Out of an abundance of caution, Homeland Security determined the flight would not be allowed to land in Boston," a U.S. Homeland Security Department official said in Washington, speaking on condition of anonymity because of the sensitivity of the situation.
He said no unusual activity was reported aboard the plane.
The man, traveling with three women identified as his mother and two sisters, was taken into custody for questioning by British and U.S. authorities, the Homeland Security official said.
The official, who did not know the suspect passenger's age or nationality, said the three women traveling with him were not taken into custody.
But London's Metropolitan Police said port and border control officials were questioning four passengers removed from the flight.
Police did not specify who they were.
The U.S. Transportation Security Administration's "no-fly" list was established after the Sept. 11, 2001, attacks to prevent people who may have terrorist ties from boarding commercial flights.