Former US president Barack Obama and former secretary of state Hillary Clinton were among the targets of suspected package bombs delivered to several high-profile Democrats and CNN, which the FBI said it was investigating as an act of terrorism.

At least eight suspicious parcels were intercepted before reaching any intended recipients, including Obama's attorney general, Eric Holder, former CIA director John Brennan and prominent Democratic Party donor George Soros.

Two packages were sent to California Congress member Maxine Waters, the FBI said. Investigators were trying to track down another suspicious parcel they believe was addressed to Obama's vice-president, Joe Biden, a federal official told Reuters late yesterday...