BEIRUT - Fierce clashes raged on Tuesday inside the historic Umayyad Mosque in Syria’s second city Aleppo, as rebels battled troops at a police academy elsewhere in the province, a watchdog said.The Syrian Observatory for Human Rights said rebels had pushed into the regime-held mosque from their positions at the southern entrance, and were also fighting troops in the Unesco-listed Old City. A military source earlier reported heavy fighting and said rebels had detonated an explosive near the southern outer wall of the mosque to break into the courtyard.Elsewhere in Aleppo province, rebels pushed into the grounds of a major police academy and seized one of its buildings after a fierce two-day siege in which more than 70 combatants were killed, the Observatory said. The academy, located near the town of Khan Assal, is one of the last regime bastions in the province.Regime forces retaliated with air strikes on rebels around the school and reinforcements were seen heading towards Khan Assal, according to the watchdog, which collects its reports from a network of activists and medics on the ground. Air strikes were also reported in the southern province of Daraa, the eastern outskirts of Damascus, the northwestern province of Idlib, the northern province of Raqa and the eastern city of Deir Ezzor.An AFP correspondent in Deir Ezzor said two MiGs flew repeated low-level sorties over the Sheikh Yassin neighbourhood for more than three hours during the morning, droping at least 50 bombs on rebel positions. The strikes were accompanied by shelling from light and heavy artillery, as troops tried to open a breach in rebel defences.In Damascus, three young children were killed by army shelling on the eastern district of Jobar, the Observatory said, giving an initial toll of 97 people killed nationwide on Tuesday. On the political front, Russian Foreign Minister Sergei Lavrov held talks with US Secretary of State John Kerry and said the Syrian opposition should enter into talks with the regime of President Bashar al-Assad and put together a negotiating team. “We are counting on the opposition, who will be meeting with representatives of Western and a number of regional countries in Rome, to also declare itself in favour of dialogue because they have voiced contradictory statements on that account and not only declare but also name their negotiating team,” the Interfax news agency quoted Lavrov as saying in Berlin.Delegates from 56 nations working on sanctions against Syria, agreed Tuesday in Sofia to ramp up political pressure against Bashar al-Assad’s regime in what officials called their strongest declaration yet.The “Friends of Syria” international working group on sanctions, which includes Western and Arab countries, called “on all members of the international community, especially members of the United Nations Security Council, to take swift, responsible and resolute action... with a view of depriving the regime of resources and instruments essential to its campaign of violence.” With China and Russia blocking common Security Council action, the group’s meeting in Sofia — the sixth since its inception — also encouraged members to increase unilateral sanctions to tighten the noose around the regime. UN under secretary general Jeffrey Feltman said that a record 150,000 people fled Syria this month to escape the worsening conflict now trapped in a “destructive military spiral.” The top UN official also pointedly told the UN Security Council that abuses committed by President Bashar al-Assad’s forces were “significantly” worse than those of the opposition, even though both could face war crimes charges.According to The New York Times, Saudi Arabia has been supplying Syrian rebels battling the regime of President Bashar al-Assad with arms bought from Croatia. Citing unnamed US and Western officials, the newspaper reported late Monday that the Saudi-financed “large purchase of infantry weapons” was part of an “undeclared surplus” of arms left over from the Balkan wars in the 1990s and that they began reaching anti-regime fighters via Jordan in December. That was when many Yugoslav weapons started showing up in YouTube videos posted by rebels, it said.Since then, The Times added, officials said “multiple planeloads” of weapons have left Croatia, with one quoted as saying the shipments included “thousands of rifles and hundreds of machine guns,” as well as an “unknown quantity of ammunition.”State Department deputy acting spokesman Patrick Ventrell said he had seen the reports, but was not in any position to comment on whether they were true.