The Islamic State is reportedly trying to use 43 Christian families, stranded in Raqqa with other minority religious groups, as human shields as U.S-led coalition forces intensifies its airstrikes on the group's headquarters in the region, according to reports.

Activist-journalist group Raqqa Is Being Silently Slaughtered (RBSS) reported via social media Tuesday that ISIS officials are forcibly preventing the city's few remaining Christians and Armenians from leaving, as Syrian government forces and various other U.S.-backed militias continue to retake territory from the terrorist group.

"The suffering of Christians began with ISIS control of Raqqa," said RBSS on its website. "ISIS looks at Christians as infidels loyal to the West more than their loyalty to their homeland which they live."

According to the group, Christian families in Raqqa numbered as many as 1,500 prior to the rise of ISIS. The Syrian city has been a de facto capital for ISIS since its rise in 2014, the Daily Caller reported.

A Kurdish-Arab alliance operating along the Syria-Turkey borderline said ISIS "is about to be besieged by the U.S-backed Syrian Democratic Forces (SDF)."

On Thursday, the SDF reported advancements in the oil-rich area between Deie ez-Zor province and Raqqa, northeast Syria, subsequent to clashes with the radical group ISIS, military sources told local papers.

The Syrian army forces loyal to President Bashar al-Assad were also reportedly progressing towards the Syrian desert areas subsequent to its control over the ancient city of Palmyra.

Syrian rebel groups controlled the city of Raqqa in March 2013 after battles with Syrian army forces. It was the first province controlled by rebels in the Syrian conflict since 2011. However, the city then fell to ISIS militants who expelled Syrian rebels from whole province.

Last May, ISIS extremists abducted Father Jack Murad, head of Mar Alyan monastery in al-Qaryatain near Homs, after seizing the nearby ancient city of Palmyra in central Syria. At that time, the terror group kidnapped over 220 civilians, including at least 60 Christians, after seizing al-Qaryatain, according to local activists.

The terror group has been carrying out atrocities against Christians on the grounds of apostasy, confiscating their property and enslaving their women, said the reports.