Dylann Roof, the man accused of murdering nine black people at a bible studies class in a Charleston church, will be indicted on a federal hate crime charge, Associated Press reported.

Speaking on condition of anonymity, an official close to the investigation told the agency that a grand jury would indict 21-year-old Roof.

Previously, officials said that the shootings met the legal requirements for a hate crime.

Before the attack on the Emanuel African Methodist Episcopal Church on 17 June, Roof posted pictures of himself posing with the Confederate flag, and a 'manifesto' in which he outlined his racist views.

Roof was earlier indicted on nine counts of murder, three of attempted murder, and a firearms charge. FBI hate crimes charges typically serve as a "backstop" for state and local authorities, according to the FBI website. However South Carolina is one of five US states that does not have its own hate crime legislation.

With the case to be tried in a state court, the FBI is likely to offer investigatory efforts in a supporting role and monitor court proceedings "to ensure that the federal interest is vindicated," reports the Charleston Post and Courier.