At least 500 members of Iraq's Yazidi minority in northern Iraq have been been killed by ISIL, including some who have been buried alive, an Iraqi government minister said on Sunday. 

According to Iraq's human rights minister Mohammed Shia al-Sudani, ISIL militants have buried hundreds of Yazidis in mass graves, as well as some women and children who were still alive. He also said about 300 Yazidi women had been forced into slavery. 

"We have striking evidence obtained from Yazidis fleeing Sinjar and some who escaped death, and also crime scene images that show indisputably that the gangs of the Islamic States have executed at least 500 Yazidis after seizing Sinjar," Sudani told Reuters. "Some of the victims, including women and children were buried alive in scattered mass graves in and around Sinjar."

In remarks to the media Saturday, President Barack Obama said dealing with ISIL in Iraq is a "long-term project." 

"There is no doubt that their advance, their movement over the last several months has been more rapid than the intelligence estimates and I think the expectations of policy makers both in and outside of Iraq," Obama said. "Part of that is not a full appreciation of the full degree to which the Iraq security forces, when they are far away from Baghdad, did not have the incentive or capacity to hold ground against an aggressive adversary."