Three men have been arrested since May of last year on charges of plotting attacks in New York City for the Islamic State in Iraq and the Levant (Isil) during the summer of 2016, US prosecutors said on Friday.

The planned attacks, which were thwarted by law enforcement, included detonating explosives in Manhattan's Times Square and in the city's subway, according to the office of acting US Attorney Joon Kim in Manhattan.

One of the men, 19-year-old Canadian citizen Abdulrahman El Bahnasawy, has been in US custody since May 2016, when he was arrested in New Jersey. He pleaded guilty to terrorism charges in October 2016, the prosecutors said.

Talha Haroon, a 19-year-old U.S. citizen, was arrested in Pakistan, where he lives, around September 2016, and Russell Salic, a 37-year-old citizen of the Philippines, was arrested in that country in April of this year, according to Mr Kim's office.

Prosecutors said they expected Haroon and Salic to be extradited to the United States to face the charges, which include conspiracy to commit acts of terrorism and to support a terrorist organisation. If convicted of the most serious charges, they face a maximum sentence of life in prison.