The suspect in a series of weekend bombings in New York City and New Jersey was charged late yesterday with five counts of attempting to murder a police officer.

Ahmad Khan Rahami was also charged by the prosecutor in Union County, New Jersey, on weapons-related offences, news reports said.

Police believe the 28-year-old naturalised US citizen from Afghanistan is behind the bombings, but charges directly related to those crimes have yet to be filed.

The charges filed in Union County stem from a shoot-out Monday with police in Linden, New Jersey, that ended with Ahmad being taken into custody. Two police officers were wounded in the gun battle. Ahmad was wounded in the leg.

FBI assistant director William Sweeney said authorities had "directly linked" Ahmad to the explosive devices found in New York and New Jersey.

He said five individuals had been questioned but not held, adding that there are no indication that a terrorist cell was operating in the area.

New York City Mayor Bill de Blasio said investigators were not seeking any other individuals, but said investigators "have every reason to believe" the bombings in his city were an act of terrorism.

New York governor Andrew Cuomo said police were led to Ahmad by DNA and fingerprints.

Ahmad also travelled to Pakistan and had a wife there, Cuomo said on CNN. He came to the United States as a child in 1995 and became a naturalised US citizen in 2011, according to law enforcement officials quoted by news reports.

Ahmad was found sleeping in a doorway and opened fire with a handgun on the officer who woke him up, Linden police captain James Sarnicki told broadcaster NBC News.

Rahami was named by the FBI as wanted for questioning in the bombing, which wounded 29 people late Saturday in Manhattan. A second, unexploded device made with a pressure cooker was found minutes later blocks from the blast site.

Police discovered several explosive devices late Sunday inside a bag at a train station in Elizabeth, New Jersey, just north of Linden.

One of the devices blew up early Monday, but didn't cause casualties, as bomb experts were working to defuse it, the FBI said.

Before the blast in Manhattan, a bomb went off Saturday along the planned route of a US Marines-sponsored charity run in Seaside Park, New Jersey, 100km south of Elizabeth. No one was injured.

The timing of the incidents - one week after the anniversary of the Sept 11, 2001, terrorist attacks and seven weeks before the US presidential election - prompted New York officials to tighten security.

The UN General Assembly opens today at UN headquarters, which is just 3km from the site of the blast in Manhattan.

De Blasio on Sunday vowed a "bigger than ever" police presence to protect the United Nations.

US President Barack Obama is scheduled to be one of the first speakers this morning.

Speaking in New York as news of Ahmad's capture broke, Obama said he was briefed by the FBI director and had spoken to the governors of New York and New Jersey.

He reassured New Yorkers and Americans across the country "that our counterterrorism and law enforcement professionals at every level - federal state and local - are working together around the clock to prevent attacks and to keep us safe".

- dpa