The Syrian military dropped leaflets in the northwestern province of Idlib on Thursday, urging residents to give up their opposition to President Bashar al-Assad.
The operation was conducted as regime forces shelled rebel and jihadi positions in the province.
Idlib is the largest area of Syrian territory that remains in rebel hands, with thousands of fighters having relocating there under previous evacuation agreements.
The leaflets, dropped in rural valleys near Idlib city, told residents: "Your cooperation with the Syrian Arab Army will release you from the rule of militants and terrorists, and will preserve your and your families' lives."
"The fate of your family, children and future depend on your decision," it added.
Fears of 'bloodbath'
The United Nations on Thursday appealed for talks to avert widespread slaughter in the province.
"The war cannot be allowed to go to Idlib," UN humanitarian advisor Jan Egeland told reporters in Geneva. "This war must end not in a bloodbath but in agreements.”
The government has said that a deal would grant an amnesty to rebels, unless private lawsuits were brought against them. Under the terms, they would have to give up weapons.
Such deals, normally negotiated by Russia, have acted as a tool to help the Syrian government regain control in other areas, from which many rebel fighters and civilians were relocated to Idlib.
The British-based Syrian Observatory for Human Rights said government forces had already arrived nearby for a possible attack, with the shelling taking place in preparation for the assault.
Read more: From Madaya to Idlib - 'defeated but safe'
Last month, the Syrian government evacuated pro-Assad villages in the region.
Idlib, which has been out of regime control since 2015, lies along the border with Turkey but is almost totally surrounded by government-held territory. Some 60 percent of the area is now held by the jihadi-led Hayat Tahrir al-Sham (HTS) alliance, with the rest controlled by other opposition groups.
rc/amp (AFP, Reuters)