Iraqi Prime Minister Nouri al-Maliki spoke out Sunday against the persecution of Christians in his country by the Islamic State of Iraq and al-Sham (ISIS), also known by the Arabic acronym DAISH or Daesh.

The Islamic Dawa Party Secretary-General condemned the terrorists' killings and the destruction of Christian and Shiite Muslim houses of worship, villages, and historical sites across Iraq and Syria.

"What is being done by the Daesh terrorist gang against our Christian citizens in Ninevah Province, and their aggression against the churches and houses of worship in the areas under their control reveals beyond any doubt the extremist criminal and terrorist nature of this group," al-Maliki said in a statement.

A video posted on YouTube July 9 shows a tomb being destroyed with a sledgehammer, and Nineveh officials said the grave is "almost certainly" that it is that of Jonah. The grave of biblical figure Seth, son of Adam and Eve, was also destroyed.

According to Nineveh Police spokesman Major Ahmed alObaidi, the tomb defacements were part of a series of attacks in Mosul that occurred on a single day.

"They torched 11 churches and monasteries out of 35 scattered across the city of Mosul, and hours later destroyed statues of poets, literary and historical figures of which Mosul has long been proud," he told Iraqi News on July 4.

Prime Minister al-Maliki said the frequency and cruelty of the attacks is evidence that there are not just pockets of extremists in the organization.

"Those people, through their crimes, are revealing their true identity and the false allegations made here and there about the existence of revolutionaries among their ranks," his statement read.

The condemnations come one day after a deadline was imposed by ISIS on area Christians. The extremists ordered civilians to convert to Islam, pay a tax, leave the country, or be put to death. Hundreds of thousands of Iraqis have fled the country because of attacks and persecution at the hands of ISIS.

Many of the refugees have entered Kurdistan, an autonomous region in northern Iraq. The Prime Minister urged neighboring countries to provide the displaced families with "all the necessities for a decent life," and for "the whole world to tighten the siege on those terrorists and stand as one force to confront them."