DAMASCUS, Nov. 16 (Xinhua) -- The U.S.-backed Syrian Democratic Forces (SDF) has amassed around 1,700 fighters over the past 24 hours as part of the preparation for another wave of attack on Islamic State (IS) positions in eastern Syria, a war monitor reported Friday.

Big military reinforcement was brought in by the Kurdish-led SDF to the eastern countryside of Deir al-Zour province, as the group is preparing to launch the second wave of attack to dislodge IS from its last pocket on the eastern bank of Euphrates River, according to the Syrian Observatory for Human Rights.

The Britain-based watchdog group said that the new offensive against IS' last pocket in eastern Syria could start soon.

The U.S.-led warplanes have also been paving the way for the ground troops near the IS pocket in the eastern Euphrates by striking the villages under IS control.

A day earlier, the observatory, which says it relies on a network of activists on the ground, said that as many as 105 people had been killed over the past seven days as a result of U.S.-led airstrikes on IS-held areas.

Eighty children and women were among those killed in the relentless airstrikes, it said.

Airstrikes on the last IS-held pocket on the eastern bank of Euphrates River have recently intensified as the U.S.-backed Kurdish militias were planning a second wave of attacks on the IS after a failed attempt on Sept. 10.

On Saturday, the Syrian Foreign Ministry renewed in a statement its call on the UN to form "an independent international mechanism" to investigate the "crimes of the Washington coalition" and punish the perpetrators.

The Syrian government has long questioned the intention of the U.S.-led operations in this oil-rich area inside Syria.