Iraqi soldiers and pro-government Shiite militias have been massing for days in preparation for an attack on ISIS strongholds along the Tigris River to the north and south of Tikrit, hometown of executed former dictator Saddam.
Tikrit, about 150 km north of Baghdad, has been controlled by the ISIS Sunni Muslim radicals since they swept through northern Iraq in June, scattering Iraq's security forces.
Tribal leaders said ISIS fighters had detained 42 Sunni tribesmen in the village of Rubaidha on Tuesday whom they suspected of being ready to take up arms against them.
"Iraq's military said around 2,000 Shiite militia fighters, known as the Popular Mobilisation, had arrived near Tikrit in preparation for a major operation against ISIS."
"They broke into the houses and asked for mobiles," said Hatam al-Obeidi, a Rubaidha resident who escaped to the town of Tuz Khurmatu on Wednesday.
"They were checking everything in the mobiles that might show that the owner is against them," he said, adding that his own telephone had been returned to him after a gunman told him he was "clean".
Last week, insurgents detained 56 men accused of belonging to a government-backed Sunni militia, said Abu Kareem al-Obeidi, who left Rubaidha for the neighboring Diyala province to avoid abduction.
Iraq's military said around 2,000 Shiite militia fighters, known as the Popular Mobilisation, had arrived near Tikrit in preparation for a major operation against ISIS.
Raed Jabouri, governor of Tikrit's Salahuddin province, said on Tuesday that 5,000 fighters from the security forces and the Popular Mobilisation - formed last year with Iranian support after the rout of the army - would join "the operation to liberate Tikrit".
Witnesses said the militants had on Wednesday blocked three main entrances to the south, west and north of Tikrit with 4-metre concrete blast walls.
They also covered a bridge across the Tigris with about 1 meter of sand in the hope of absorbing the impact of bombs.
The witnesses saw a stream of SUV vehicles, apparently containing detainees, heading north toward the northern, ISIS-controlled city of Mosul.
After months of air strikes by the United States and its Western and Arab allies, ISIS is on the defensive in several parts of the "caliphate" it declared in swathes of Iraq and Syria. In Diyala, officials say they have all but driven ISIS out.
ISIS militants have abducted at least 150 people from Assyrian Christian villages in northeastern Syria they had raided, Christian Syrian activists said, Reuters reported.
Because of heavy kurds attacks to terrorists ISIS militants are planning to murder 150 Christian hostages they kidnapped after sweeping through villages in Syria if the U.S. does not stop air strikes, it has been reported.
Some other informed figures says ISIS want to Prisoner Swap with Kurdish Fighters, Newsweek reports.
The abductions of the 150 Christians took place yesterday after ISIS seized two Assyrian communities from Kurdish forces in the northeast province of Hassakeh.