Iraq has exhumed the remains of 47 people believed to have been massacred by jihadists from mass graves in Tikrit, the human rights ministry’s spokesman said Tuesday.

“The number of remains that were exhumed so far is 47, and they were found in 11 mass graves,” Kamel Amin told AFP, adding that the number is expected to rise.

Amin said they are believed to have been victims of the infamous Speicher massacre, named for the military base near which up to 1,700 mostly Shi’ite recruits were abducted by the Islamic State (ISIS) jihadist group last year.

But DNA testing is required to confirm their identity, he said.

The killing of the recruits – which the jihadist group documented in photos and videos posted online – stoked widespread anger and helped rally support for the battle against ISIS.

The mass grave sites were discovered after Iraqi forces retook the city of Tikrit last week in their biggest victory so far against ISIS.

ISIS led an offensive last June that overran large areas north and west of Baghdad, but Iraqi security forces and allied paramilitaries have succeeded in regaining significant ground.