US President Barack Obama has for the first time publicly accused an offshoot of al-Qaeda over the alleged Christmas Day bomb plot to blow up a US plane. In his weekly radio and video address posted on the White House website early today, Mr Obama said it appeared Yemen-based al-Qaeda in the Arabian Peninsula had armed and trained the accused 23-year-old Nigerian, Farouk Abdulmutallab. The group admitted responsibility in an internet statement last week.Mr. Obama said all those involved in the attempted act of terrorism on Christmas must know that they too will be held to account. Mr Obama has already condemned lapses that allowed the accused, who was on a terror database to board the jet.