BEIRUT (AP) -- Islamic State militants seized the ancient Syrian city of Palmyra on Sunday from government troops despite a wave of Russian airstrikes, opposition activists and the group reported, a major advance after a year of setbacks in Syria and neighboring Iraq.
The group's new push came hours after government troops and Russian air raids pushed the group out the city. IS militants regrouped and attacked the city from multiple fronts, forcing government troops to retreat. Palmyra opposition activists said the militants were going door to door in the city, looking for remnants of government forces.
State news agency SANA quoting an unnamed military official saying that the militant group received reinforcements from its de-facto capital in Raqqa, enabling it to attack with "large numbers" against military checkpoints around the city.
Backed by Russian air power, the Syrian government had recaptured Palmyra, home to towering 2,000-year-old ruins, amid great fanfare in March. But the militants have been steadily advancing in recent days while the government has been focused on a major offensive against rebels in the northern city of Aleppo.
The Britain-based Syrian Observatory for Human Rights and the Palmyra Coordination group said IS militants fought their way into the town in a multi-pronged assault, forcing government forces to retreat to the south. A map by the Observatory shows the areas in control of IS to extend east, south and north of Palmyra, securing a number of strategic hills around the city and expanding the group's presence in rural Homs. Palmyra lies in Syria's largest province, Homs, which is mostly under government control.
Osama al-Khatib, of the activist-run Palmyra Coordination group which keeps in touch with residents in the city, said remaining government and allied troops were escaping from the southwestern edge of the city where the ancient ruins are. He said the few remaining families in the city are also attempting to escape. Another activist-run platform, Palmyra News Network, said intensive airstrikes followed the IS takeover of the city.
Russia had earlier claimed to have repelled an IS attack on Palmyra, saying it had launched 64 airstrikes overnight that killed 300 militants. But hours later, the activists said IS had seized a castle just outside the town that overlooks its famed Roman-era ruins.
Palmyra was a major tourist attraction before the civil war broke out in 2011 and is home to world-famous Roman ruins. IS seized the town last year and held it for 10 months. During that time it dynamited a number of temples and destroyed other artifacts.
The dramatic reversal in Palmyra comes days after IS militants in the Iraqi city of Mosul launched a major counterattack that surprised Iraqi soldiers, killing at least 20 and halting their advance. Iraqi special forces units have entered the eastern outskirts of the largest remaining IS-held city, but their advance has been greatly slowed by both a desire to limit civilian casualties and the resilience of the IS fighters.
Over the last year, IS has suffered a string of defeats in both Syria and Iraq, losing several towns and cities it had captured in 2014.
U.S. Defense Secretary Ash Carter arrived in Baghdad earlier Sunday on an unannounced visit to assess the progress of the Mosul battle. He was to meet with American commanders and Iraqi leaders.
The capture of Palmyra last year by Syrian troops and Russia air force was seen as a major triumph for the government, which has had little success in battling militant group. After taking Palmyra, the two states turned their attention to wiping out the internal opposition in Damascus and Aleppo. After tightening the siege on the eastern part of Aleppo city, the most prized urban stronghold for the opposition, government and allied troops have been steadily carving into the besieged enclave in a ground offensive that began late November.
Syrian media reported Sunday that of the original 45 square kilometers (17 square miles) rebel-held enclave, only 7 square kilometers (4 square miles) remain in opposition hands.