Singapore's Prime Minister Lee Hsien Loong has sent his condolences to US President Barack Obama following the twin bombings at the Boston Marathon that killed three people and injured more than 100.

In his condolence letter to Mr Obama, Mr Lee wrote: "I was shocked to learn about the bomb attacks at the Boston Marathon. There is no place in the world for such senseless violence."

"On behalf of the Government and people of Singapore, I offer my deepest condolences to the victims, their families and all Americans on this terrible tragedy.''

Mr Lee also said "Singapore stands alongside the Government and people of the United States in opposing such acts. Our thoughts are with you and your people during this period of grief''.