New York, Sep 20 (IANS): Security in New York city ratcheted up to the highest level on Monday following the bomb attacks and the discovery of explosives planted in the city and New Jersey.

The heightened security will be "probably the largest security presence ever amassed," Governor Andrew Cuomo said.

According to Cuomo, New York's massive police force, about 34,500 uniformed officers, will be bolstered by an additional 1,000 state police and National Guard members, who will patrol bus terminals, airports and subway stations, along with more FBI and city police, USA Today reported.

New Yorkers will see more "heavily trained officers and heavily armed officers" on the streets and in the subways, Mayor Bill de Blasio told a Monday news conference.

The city increased its anti-terror force by 500 people last year.

"You will see bags being checked, bomb-sniffing dogs," he said.

While the arrest Monday of alleged Afghan-immigrant bomber Ahmad Khan Rahami, 28, in Linden, New Jersey, gave some sense of relief, New York City Police Commissioner James O'Neill said his department would not let up.

"We always have to be in a state of alert in New York city," he said, adding "We are the number one target in the world."

New York police believed that Rahami is the man who appears in videos taken by security cameras on 23rd Street in the Chelsea neighbourhood of Lower Manhattan, where on Saturday a bomb exploded that injured almost 30 people on 27th Street, and where another device was found that did not detonate.

New Jersey authorities also believe that he might be linked to the bomb explosion early Saturday in the town of Seaside Park, New Jersey.

Jeh Johnson, secretary of Homeland Security, had already declared the gathering of world leaders for the ongoing 71st UN General Assembly session as "national special security event", which brings with it thousands of extra department officers led by the Secret Service.

Among the heads of state in town this week to discuss the world's refugee situation and other matters were Premier Li Keqiang of China and Prime Minister Haider al-Abadi of Iraq. President Obama also arrived in New York for the meeting, USA Today reported.

"Our counterterrorism and law enforcement officials at every level - federal, state and local - are working together around the clock to prevent attacks and to keep us safe," Obama said on Monday night.