Image copyright AP Image caption Dias Kadrybayev will go to prison for 72 months

A friend of Boston bomber Dzhokhar Tsarnaev, has been sentenced to 72 months in prison for obstructing the investigation into the attacks.

Dias Kadyrbayev, who pleaded guilty last year, apologised before being sentenced, and said he was ashamed.

He had removed Tsarnaev's backpack, containing emptied fireworks, from their student accommodation, hours after police appealed for information.

Three people were killed and 260 injured in the bombings.

Kadyrbayev, who is a Kazakhstan native, had been seeking a lighter sentence as part of his plea.

Prosecutors had said they would ask for no more than seven years in a federal prison for Kadyrbayev, who was 20 when he pleaded guilty.

The backpack, and Tsarnaev's laptop, were removed from a dormitory room at the University of Massachusetts-Dartmouth, hours after the FBI released photographs of the bombing suspects.

Later, the items were found in a Massachusetts landfill.