BEIRUT (Reuters) - Syrian government forces advanced into Palmyra on Saturday with heavy support from Russian air strikes, taking control of several districts in a major assault against Islamic State fighters, Syrian state media and a monitoring group said.

Forces loyal to Syria's President Bashar al-Assad flash victory signs and carry a Syrian national flag on the edge of the historic city of Palmyra in this handout picture provided by SANA on March 26, 2016. REUTERS/SANA/Handout via Reuters

Television footage showed waves of explosions inside Palmyra and smoke rising from buildings, as tanks and armored vehicles fired from the outskirts.

The Syrian Observatory for Human Rights said it was the biggest assault in a three-week campaign by the Syrian army and allied militia fighters to recapture the desert city and open up the road to Islamic State strongholds further east.

Observatory director Rami Abdulrahman said Syrian soldiers and allied militias had taken control of one-third of Palmyra, mainly in the west and north, including part of the ancient city and its Roman-era ruins. Soldiers were also fighting on a southern front, he said.

Syrian media and Arab television channels broadcasting from the slopes of Palmyra’s medieval citadel, one of the last areas of high ground seized by the army on Friday, said troops had advanced inside Palmyra and had taken several neighborhoods.

The recapture of Palmyra, which the Islamist group seized in May 2015, would mark the biggest reversal for Islamic State in Syria since Russia’s intervention turned the tide of the five-year conflict in President Bashar al-Assad’s favor.

The group and al Qaeda’s Syrian branch the Nusra Front are excluded from a month-long cessation of hostilities that has brought a lull in fighting between the government and rebels battling Assad in western Syria.

The limited truce has allowed some aid deliveries to get to previously inaccessible areas under siege. The International Committee for the Red Cross said on Saturday it brought food and hygiene items to three areas of south Damascus the day before.

Peace talks have also resumed in Geneva, but progress has been slow, with the government and its opponents disagreeing fundamentally on the terms of a political transition, including whether Assad must leave power.

Russia, which sponsored the talks along with the United States, has withdrawn some forces from Syria but has strongly supported the Palmyra offensive, saying this week that a Russian special forces officer was killed in combat near the city.

Russian news agencies quoted the defense ministry in Moscow as saying Russian jets had made 40 sorties around Palmyra in the last 24 hours, hitting 158 Islamic State targets and killing more than 100 militants.

RESTORING THE TEMPLES

Palmyra had a population of 50,000 according to a census more than 10 years ago. Those numbers were swelled hugely by an influx of people displaced by Syria’s conflict, which has raged since 2011, but most fled when Islamic State took over.

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Recapturing the city would open up eastern Syria, where Islamic State controls most of the Euphrates Valley provinces of Deir al-Zor and Raqqa, to the army.

“Our heroic forces are continuing to advance until we liberate every inch of this pure land,” a soldier told state-run television in a broadcast from the slopes of the citadel, which overlooks the city’s monumental ruins.

In August, Islamic State fighters dynamited two ancient buildings, the temples of Bel and Baal Shamin, which had stood as cultural landmarks in Palmyra for nearly two millennia. The United Nations described their destruction as a war crime.

Antiquities chief Maamoun Abdelkarim said on Saturday Syria would try to restore the temples, as well as funeral towers and a triumphal arch which were also blown up last year.

“We will rebuild them with the stones that remain, and with the remaining columns,” he told Reuters in Damascus. “(We will) bring life back to Palmyra”.

He also said that recent film from Palmyra, including drone footage, revealed that many structures were still standing including the walls around the Temple of Bel, the amphitheatre and the long colonnaded avenue.

Saturday’s assault against Islamic State in Palmyra came a day after the United State said it had killed several senior leaders including Abd ar-Rahman al-Qaduli, described as Islamic State’s top finance official and aide to its leader.

Iraqi and U.S. sources said the group would struggle to replace Qaduli, a veteran jihadist with a bounty of $7 million on his head - second only to the $10 million offered for Islamic State leader Abu Bakr al-Baghdadi.