DAMASCUS, Syria -- Syrian government forces recaptured the ancient city of Palmyra on Sunday, scoring an important victory over Islamic State fighters who waged a 10-month reign of terror there and dealing the group its first major defeat since an international agreement to battle terrorism in the fractured nation took effect last year.

The city known to Syrians as the "Bride of the Desert" is famous for its 2,000-year-old ruins that once drew tens of thousands of visitors each year before IS destroyed many of the monuments. The extent of the destruction remained unclear. Initial footage on Syrian TV showed widespread rubble and shattered statues. But Palmyra's grand colonnades appeared to be in relatively good condition.

The government forces were supported by Lebanese militias and Russian air power. The Islamic State now faces pressure on several fronts as Kurdish ground forces advance on its territory in Syria's north and government forces have a new path to its de facto capital, Raqqa, and the contested eastern city of Deir el-Zour.

International airstrikes have pounded IS territory, killing two top leaders in recent weeks, according to the Pentagon. Those strikes have also inflicted dozens of civilian casualties.

In Iraq, government forces backed by the U.S. and Iran are preparing a ground offensive to retake the country's second largest city, Mosul.

The fall of Palmyra comes a month after a partial cease-fire in Syria's civil war came into force. The truce was sponsored by the United States and Russia in part to allow the government and international community to focus on Al-Qaeda styled militants, among them the IS group.

In comments reported on state TV, President Bashar Assad described the Palmyra operation as a "significant achievement" offering "new evidence of the effectiveness of the strategy espoused by the Syrian army and its allies in the war against terrorism."

IS drove government forces from Palmyra in a matter of days last May and later demolished some of its best-known monuments, including two large temples dating back more than 1,800 years and a Roman triumphal archway.

State TV showed the rubble left over from the destruction of the Temple of Bel as well as the damaged archway, the supports of which were still standing. It said a statue of Zenobia, the third century queen who ruled an independent state from Palmyra and figures strongly in Syrian lore, was missing.

Artifacts inside the city's museum also appeared heavily damaged on state TV. A sculpture of the Greek goddess Athena was decapitated, and the museum's basement appeared to have been dynamited, the hall littered with broken statues.

Still, state media reported that a lion statue dating back to the second century, previously thought to have been destroyed by IS militants, was found in a damaged but recoverable condition.

Extremists beheaded the archaeological site's 81-year-old director, Riad al-Asaad, in August after he reportedly refused to divulge where authorities had hidden treasures before the group swept in. Militants viewed the ruins as monuments to idolatry.

IS also demolished Palmyra's infamous Tadmur prison, where thousands of government opponents were reportedly tortured.

Syrian state TV hailed the government's advance, and a local reporter spoke live from inside Palmyra, showing troops in the centre of the town, where some buildings had been reduced to rubble.

Syrian Culture Minister Issam Khalil described the recapture as a "victory for humanity and right over all projects of darkness."

Maamoun Abdulkarim, director of the museums and antiquities department in Damascus, said Palmyra's Great Colonnade had suffered only minor damage. "We will rebuild what you have destroyed," he said, addressing IS.

The Syrian opposition, which blames the government for the country's devastating civil war and the rise of IS, rejected that narrative.

"The government wants through this operation to win the favour of Western nations by fighting against terrorism, while obscuring its responsibility as providing the reasons for the spread of terror," said Khaled Nasser, a member of the opposition coalition that has been negotiating with the government in Geneva.

The Britain-based Syrian Observatory for Human Rights, which monitors the conflict through local activists, confirmed that IS had lost the town. Observatory chief Rami Abdurrahman said three weeks of fighting killed more than 400 IS fighters, as well as 180 troops and allied militiamen.

Residents told The Associated Press that IS evacuated all of Palmyra's civilians to other territories under its control before government forces entered the city.

"It's joyful for people to return home. Still we are sad to see damage in this historical city," said Sohban Eleiwi, a businessman from Palmyra now residing in Homs.

Other residents said they would not return to live under government rule.

"We don't hate the regime any less than we hate Daesh," said Osama Khatib, a Palmyra native who fled to Turkey three years ago after serving a jail sentence for taking part in demonstrations.

"Daesh and the regime behave the same way," he said.

Government forces had been trying to retake the town for nearly three weeks. Gen. Ali Mayhoub announced on the Syrian TV Sunday afternoon that its recapture "directs a fatal blow to Daesh, undermines the morale of its mercenaries and ushers in the start of its defeat and retreat," referring to IS by its Arabic acronym.

Government forces have advanced on a number of fronts in recent months, aided by a Russian air campaign. Moscow announced earlier this month that it would begin drawing down its forces, but said it will continue to target IS and other extremist groups.

Syria's conflict began a little more than five years ago with mostly peaceful protests against the Assad family's four-decade rule. A fierce government crackdown and the rise of an insurgency plunged the country into a full-blown civil war that has killed more than 250,000 people.

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Issa reported from Beirut. Associated Press writer Bassem Mroue in Beirut also contributed to this report.