The Boston Marathon bombing suspects had some training in carrying out their attack, according to the chairman of the US House Homeland Security Committee.

Republican representative Michael McCaul is citing the type of device used in the attack - shrapnel-packed pressure-cooker bombs - as well as the weapons' sophistication as signs of training.

Homemade bombs built from pressure cookers have been a frequent weapon of militants in Afghanistan, India and Pakistan. Al-Qaida's branch in Yemen once published an online manual on how to make one.

Mr McCaul also told Fox News Sunday that he thinks the suspects' mother played "a very strong role" in her sons' radicaliSation process and that if she were to return to the United States from Russia, she'd be held for questioning.

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