Hundreds of Syrian rebels and their relatives began evacuating the southern city of Daraa on Sunday under a deal to bring the "cradle" of the country's uprising back under government control.
The highly symbolic transfers came as Russian-backed government forces advanced in the neighbouring province of Quneitra, with air strikes pounding rebel positions perilously close to the Israeli-occupied Golan Heights.
After securing Damascus in May, President Bashar al-Assad turned his attention to rebels in the strategically vital south, where protests against his rule first erupted seven years ago.
Nearly three weeks of bombardment saw beleaguered rebels agree with Russia earlier this month to hand over Daraa province, before reaching a similar deal for its capital this week.
The regime fully regaining its rule over Daraa city will be a hugely symbolic blow to the opposition.
In 2011, teenagers were arrested for scrawling anti-Assad slogans on the walls of a school in the city, sparking mass protests against the government.
A brutal crackdown saw the movement develop into a full-fledged conflict that has since killed more than 350,000 people and displaced half the country's pre-war population.
Assad has regained much of the territory he initially lost to opposition groups, now comfortably holding more than 60 percent of Syria.
In the south, he holds 80 of Daraa province but parts of its western countryside and most of the adjacent province of Quneitra still escape his control.
On Sunday, regime forces battered Quneitra province with hundreds of missiles and seized the town of Masshara, according to the Observatory.
The clashes had left 18 regime forces and 13 rebels and allied jihadists dead, the monitor said.
Four air strikes also hit an opposition position in Quneitra that lies within four kilometres (less than three miles) from the sensitive buffer zone with the Israeli-annexed Golan Heights.
Golan Heights - locator map
The Observatory said they were the first strikes in the area in over a year, when Russia, the US, and Jordan agreed a ceasefire deal for parts of the south.
Around 160,000 people who were displaced by the regime's offensive on Daraa are still trapped in Quneitra, near the border with the Golan.
Israel has been on high alert in recent weeks amid the spike in hostilities in the south.
The Israeli army said on Friday it had fired a missile and "very probably" destroyed a drone flying over the demilitarised zone between Israel and Syria, after intercepting another drone on Wednesday.