ELIZABETH, NJ/WASHINGTON - The father of the Afghan-born man arrested after weekend bombings in New York and New Jersey reported concerns about his son to the FBI in 2014, but officials took no action after reviewing the complaint, the father and law enforcement officials said on Tuesday.

US authorities on Tuesday investigated whether Ahmad Khan Rahami, the naturalized American citizen captured on Monday in New Jersey after a shootout with police, had accomplices in the bombings or if he was radicalized during trips to Afghanistan and Pakistan.

"The investigation is active and ongoing, and it is being investigated as an act of terror," US Attorney General Loretta Lynch said in Lexington, Kentucky.

Rahami was suspected in weekend bombings, including a blast on Saturday night in New York's crowded Chelsea neighborhood that wounded 29 people, and two in suburban New Jersey including one earlier on Saturday near a Marine Corps charity run in Seaside Park that caused no injuries.

His father, Mohammad Rahami, briefly emerged on Tuesday from the family's restaurant in Elizabeth, New Jersey, telling reporters, "I called the FBI two years ago."

A US law enforcement official confirmed the elder Rahami had twice met with the FBI, first saying that he was worried his son was hanging out with people who might have connections to militants, but two weeks later contending his real concern was that the son was associating with criminals.

The FBI tried to check out the father's story, and conducted what officials now describe as an "assessment" of that information. However, investigators found no evidence to prompt a full-scale investigation into the son, and the initial investigation was closed without action, the law enforcement official said.

At the time, the son was being held on an assault charge for stabbing his brother during a domestic dispute, another law enforcement official said.

Rahami, 28, was arrested on Monday in Linden, New Jersey, not far from Elizabeth, where his family lived above their storefront First American Fried Chicken restaurant. The family was known to local authorities for frequent disputes related to the restaurant, which had received noise complaints for staying open very late into the night.

The bombings put New York, the largest US city, on edge and fueled a political debate about US security seven weeks before the presidential election, with candidates Donald Trump and Hillary Clinton again clashing on the threat posed by Islamic militants.

Two US officials said Rahami had traveled to Afghanistan and to Quetta, Pakistan. The official, and other US security sources, said Rahami underwent additional security screening upon returning from abroad but passed on every occasion. One of the officials, who specializes in counter-terrorism, said the "secondary" screening included asking Rahami where he had gone and for what purpose.

"There could have been a more intensive holding and screening in that situation," US Senator Angus King, an independent from Maine, told CNN. "The problem is what happened next didn't really go into any depth."

Rahami's wife left the United States a few days before the bombings, CNN reported, citing a law enforcement source.

Rahami had emailed US Representative Albio Sires of New Jersey, whose congressional district includes Elizabeth, in 2014 from Pakistan, raising concerns about his wife's visa issues, said Mark Gyorfy, a spokesman for the congressman.