The so-called Syrian Observatory for Human Rights said Daesh has pulled back to residential areas in the east of Palmyra by Thursday morning.
The terror group withdrew from most of Palmyra after laying mines across the city, said Observatory head Rami Abdel Rahman, adding that there are still Daesh bombers in the citys eastern neighborhoods.
Government forces have not yet been able to enter the heart of the city or the eastern parts, he noted.
Syrian forces, backed by the Russian air force, pushed into a western neighborhood of the city late on Wednesday after heavy clashes with Daesh.
The Syrian troops also managed to retake a palace complex to the citys southwest.
Earlier in the day, an unnamed Syrian military source told Reuters that the Syrian troops, backed by Russias air cover, had advanced to the outskirts of Palmyra, also known in Arabic as Tadmur, in the last few days and their entry to the city will begin very soon.
The developments came on the same day as the Syrian military announced the recapture of an area called the Palmyra triangle a few kilometers west of the city.
[caption id="" align="alignnone" width="555"]
The director of Syrias Antiquities Department Maamun Abdul-Karim shows rare busts rescued from Daesh in the ancient city of Palmyra and restored in Italy, after they were returned to Syria, at the National Museum in Damascus on March 1, 2017. (Photo by AFP)[/caption]Meanwhile, Syrias official SANA news agency reported that the gain followed fierce clashes between Daesh militants and the Syrian army and its allied fighters, leaving scores of the terrorists dead or injured.
The Syrian army, backed by Russias counter-terrorism airstrikes, liberated Palmyra in March 2016, ending Daeshs 10-month grip over the city.
However, Daesh managed to seize the historic city once again in December 2016 after days of intense fighting as the Syrian military focused mainly on defeating terrorist groups in eastern Aleppo.
During both of its spells in control of Palmyra, Daesh razed ancient monuments and dismantled key parts of the city's UNESCO World Heritage ruins.
The Syrian forces have been fighting different foreign-backed militant groups wreaking havoc in the Middle Eastern country since 2011.
Over the past few months, troops have made sweeping gains against Takfiri terrorists who have lately increased their acts of violence across Syria following a series of defeats in Aleppo and elsewhere.
