SHARON - The FBI is asking for the public's help in identifying the robber in three bank robberies, including one in Sharon near the Foxboro line, which authorities say have been held up by the same man.

The man, who held up the Citizens Bank at 720 South Main St. on Sept. 1, is believed to be the same man who robbed the Merrimack Valley Credit Union on Aug. 17 and the Lowell 5 Bank in Tewksbury on Oct. 19, according to the FBI's Boston office.

The man enters the banks with his face covered and approaches the teller windows where he verbally demands money from all the tellers. He then puts the money in a case that is described as either a black laptop case or a messenger case.

He flees the bank on foot. No vehicle has ever been seen. To date, no weapon has been shown or threatened.

Witnesses described the robber as a white mn in his late 20s to his early 30s. He is 6 feet to 6 feet, 3 inches tall with a heavy build. Anyone with information is asked to call the FBI at (617) 742-5533.