A Somali-born teenager was arrested in the US last night for attempting to detonate what he thought was a car bomb at a Christmas tree lighting ceremony in Oregon.

Mohamed Osman Mohamud (19) was charged with attempting to use a weapon of mass destruction in connection with an alleged plot to bomb the annual event in downtown Portland, the Justice Department said late yesterday.

The bomb was a fake and had been provided to Mr Mohamud as part of a long-term sting by the FBI and other law enforcement agencies, federal officials said in a statement.

Officials said Mr Mohamud had been in contact with an unnamed individual believed to be in northwest Pakistan and involved in terrorist activities.

"The threat was very real," said Arthur Balizan, a senior FBI agent in Oregon. "Our investigation shows that Mr Mohamud was absolutely committed to carrying out an attack on a very grand scale."

Thousands of people attended the tree lighting in a popular Portland square lined with shops and offices. Officials said the public had never been in danger at any time during the sting operation, which lasted months.

Mr Mohamud, a naturalized US citizen and student at Oregon State University, was taken into custody near the square after he attempted to use a mobile phone to trigger what he believed was a car bomb, according to a US government complaint.

He lashed out at agents, yelling and kicking them, and had to be restrained, it said. Agents had shadowed Mr Mohamud and met him several times as the plot developed, the US government said.

He told FBI agents that he had thought of waging violent jihad, or holy war, since the age of 15, federal officials said.

Reuters