The mother of two men suspected of carrying out the Boston Marathon bombings has said she believes her sons are innocent and is "100% sure that this is set up".

Speaking to Russia Today, Zubeidat Tsarnaev alleged that her oldest son, Tamerlan, was controlled by the FBI for years.

Dzhokhar Tsarnaev, 19, is in custody after police cornered him in Watertown, near Boston.

His 26-year-old brother Tamerlan Tsarnaev, an alleged accomplice, was fatally injured in a shootout with officers earlier on Friday.