A Russian rebel group has denied any link to the deadly Boston marathon bombings.

The attack is being blamed on two Chechen suspects, brothers Dzhokhar and Tamerlan Tsarnaev, who had been living in the US.

A website used by Russia's North Caucasus rebels says their fighters are not waging any military activities against the US, and their only target is Russia.

It comes after reports said the FBI was studying possible links between the brothers, and the Caucasus Emirate movement.

Jokhar remains under heavy guard in hospital in Boston, as specialist interrogators wait to question him after his brother was shot dead by police.