BEIRUT — Combat raged near a historic mosque in the Syrian city of Aleppo Tuesday while anti-government activists reported fresh clashes near a police academy west of the city. The fighting near the Umayyad Mosque in the walled Old City of Aleppo threatened to further damage the 12th century structure, part of which was burned during clashes last year. Since July 2012, government forces and rebels seeking to topple President Bashar Al-Assad have been fighting over Aleppo, the country's largest city and a major prize in the civil war. While rebels have gradually expanded the turf under their control, fighting has left much of the city, considered one of Syria's most beautiful, in ruins. The Britain-based Syrian Observatory for Human Rights said Tuesday that rebels clashed with government forces near the Umayyad Mosque amid intense gunfire and explosions. Syria's state news agency said “terrorists” had detonated explosives near the mosque's south wall, causing “material damages” to the wall and the nearby area. Assad's regime refers to the opposition as “terrorists.” The mosque, also known as the Great Mosque of Aleppo, dates to the 12th century and sits near a medieval covered market in Aleppo's walled city, which is a UNESCO World Heritage site. The mosque was heavily damaged in October, 2012, and a fire torched the market the month before. Also Tuesday, activists reported fresh fighting near the police academy that has become a key government military installation west of the city. An Aleppo activist who goes by the name Abu Al-Hassan said via Skype that rebels coming from Idlib province to the west are now trying to clear the army from residential areas near the academy before they attack it. “Yesterday and today they have been trying to go forward but there are lots of shelling and airstrikes,” he said. The fighting has largely destroyed Aleppo and caused humanitarian conditions for the city's remaining civilians to plummet. Meanwhile, Russian Foreign Minister Sergei Lavrov slammed “extremists” in the Syrian opposition who he said were blocking the start of dialogue with Damascus by making unrealistic demands. Hours before he was due to meet John Kerry, US Secretary of State, Lavrov said recent faint hopes that dialogue was possible between the opposition and the regime of President Al-Assad had dissipated. “It seems that extremists who bet on an armed solution to the Syrian problem have prevailed in the ranks of the opposition at this time, including the so-called (Syrian) National Coalition, blocking all initiatives that could lead to a dialogue,” Lavrov said in Moscow. — Agencies