US officials have arrested a man for plotting to detonate what he thought was a massive bomb in front of the Federal Reserve building in New York.

Quazi Mohammad Rezwanul Ahsan Nafis, 21, of Bangladesh, travelled to the US with the intent of planning a terrorist attack, the FBI said.

Mr Nafis was arrested after he allegedly attempted to detonate what he thought was a 1,000lb (454kg) bomb.

There was never a threat, the FBI said, as Mr Nafis had been closely watched.

Mr Nafis is charged with attempting to use a weapon of mass destruction and attempting to provide material support to al-Qaeda.

Mr Nafis travelled to the US in January 2012 and sought out contacts to help him with the attack, officials said in a complaint filed in New Yorkon Wednesday.

One of the people he contacted turned out to be a source working for the FBI, US federal prosecutors said.

Mr Nafis was placed under surveillance, and the undercover FBI agent sold him 20 bags of what he thought were 50lb of explosives. The suspect then bought and assembled detonators and timing devices.

Officials said there had never been any actual threat.

The arrest is the latest in a series of so-called "sting" operations run by the FBI and anti-terror authorities in the US.

The Federal Reserve building, housing the US central banking organisation, is located in downtown Manhattan in New York City, blocks from the World Trade Center complex in the city's financial district.

Federal officials say Mr Nafis proposed several targets, including a high-ranking US official and the New York Stock Exchange.

In a statement intended to claim responsibility for the would-be attack, Mr Nafis allegedly said he believed the most efficient way of destroying American was to target the US economy.

Prior to the attempt, Mr Nafis alledgedly recorded a video in which he said "We will not stop until we attain victory or martyrdom", according to the complaint.

"The defendant thought he was striking a blow to the American economy. He thought he was directing confederates and fellow believers," Loretta Lynch, US Attorney for the eastern district of New York said in a statement.

"At every turn, he was wrong, and his extensive efforts to strike at the heart of the nation's financial system were foiled by effective law enforcement."

The Bangladeshi, who was living in Queens, New York, reportedly told undercover FBI officials that he had overseas connections to al-Qaeda.----

Source: http://www.bbc.co.uk/news/world-us-canada-19985987