Syrian rebels captured a strategic neighborhood near Aleppo's international airport on Saturday, putting opposition fighters in control of a key road that the regime has used to ferry supplies and reinforcements to soldiers fighting in the embattled northern city, activists said.
Elsewhere in the nation, fighting continued unabated, killing more than 60 people nationwide, according to activists.
The capturing of the Sheik Said neighborhood, southeast of Aleppo, is a significant blow to regime forces because the area includes a major road, linking the northern city with the airport. The army has used the road to supply troops.
The Britain-based Syrian Observatory for Human Rights said rebels captured the area Saturday after several days of fierce battles with Assad's troops. Rebels have previously established enclaves outside Syria's major cities to threaten the regime, including near the capital, Damascus, but they were later attacked by Assad's fighter jets and artillery.
In an effort to reverse rebels' advance in Aleppo, regime's war planes carried out several airstrikes on the Sheik Said, the Observatory said. There were no reports of casualties from the bombing.
The opposition's Western backers, including the United States, have been reluctant to supply rebels with more sophisticated weapons because of the increased influence of an al-Qaida-affiliated group among the anti-Assad fighters on the front lines. The Islamists growing prominence in the Syrian opposition has fueled fears that Muslim radicals might try to hijack the revolt that started as peaceful protests against Assad, whose family has ruled Syria for more than 40 years.
In Germany, Vice President Joe Biden said, "The opposition (to Assad) continues to grow stronger."
Speaking at an annual security conference in Munich, Biden stated the conviction of the U.S. and many others. "President Assad — a tyrant hell-bent on clinging to power — is no longer fit to lead the Syrian people and he must go," Biden said.
Assad has repeatedly brushed aside international calls to step down, characterizing its opponents as Islamic extremists who are out to destroy the country. In a speech last month, Assad outlined a peace initiative that would keep him in power.
The opposition coalition has rejected any talks with Damascus until Assad steps down. However, Moaz al-Khatib, the president of the coalition that is dominated by the Muslim Brotherhood movement, said Wednesday that he is willing to negotiate with members of Assad's regime to bring a peaceful end to the country's civil war.
Russia is Assad's longtime ally, and it has disagreed sharply with Washington and its Western allies on ways to end the bloodshed in Syria. Moscow has maintained that Assad is part of the solution to the crisis, though Russian officials have recently criticized their ally in Damascus and even mentioned the possibility of rebels winning the war.
However, Lavrov told the gathering of top security officials that Biden's statement that Assad must go was counterproductive.
"The persistence of those who say that priority No. 1 is the removal of President Assad — I think it's the single biggest reason for the continued tragedy in Syria," Lavrov said.
Syria's civil war is estimated to have claimed more than 60,000 lives since the uprising against Assad erupted in March 2011.