Activists: Battles Rage in Syria's Aleppo

Syrian troops and rebels fought the heaviest battles in months Friday Aleppo, Syria's largest city, a day after U.S. officials said Washington has authorized sending weapons to opposition fighters for the first time.

The Britain-based Syrian Observatory for Human Rights said the clashes concentrated in the eastern rebel-held neighborhood of Sakhour, calling the fighting "the most violent in months." It said troops attacked the neighborhood from two directions but failed to advance, suffering casualties.

Aleppo, Syria's commercial hub before the civil war, is near the Turkish border.

The opposition's Aleppo Media Center said troops bombarded Sakhour with tank shells and rockets before sending in troops. The fighting lasted about four hours, and then warplanes raided rebel positions in Sakhour.

The intensified fighting coincided with President Barack Obama's decision to authorize sending weapons to Syrian rebels, marking a deepening of U.S. involvement in Syria's two-year civil war.

U.S. officials said the administration could provide the rebels with a range of weapons, including small arms, ammunition, assault rifles and a variety of anti-tank weaponry such as shoulder-fired rocket-propelled grenades and other missiles. However, no final decisions have been made on the type of weaponry or when it would reach the rebels, according to the officials, who insisted on anonymity in order to discuss internal administration discussions with reporters.

Rami Abdul-Rahman who heads the Observatory said troops were trying to capture a major intersection in Sakhour that links several major roads in Aleppo including one leading to the city's airport and another to the north.

"It is a strategic area," said Abdul-Rahman. He said large numbers of rebels took part in the fighting.

The attack on Sakhour comes a week after Syrian government forces backed by Hizbullah fighters captured the town of Qusayr near the Lebanon border.

Regime forces now appear set on securing control of the central provinces of Homs and Hama, a linchpin area linking Damascus with regime strongholds on the Mediterranean coast, and Aleppo to the north.

The fight for Aleppo, a city of 3 million that was once a bastion of support for Assad, is critical for both the regime and the opposition. Its fall would give the opposition a major strategic victory with a stronghold in the north near the Turkish border. A rebel defeat would buy Assad more time, at the very least. It could also turn the tide of the civil war against the rebels.

Opposition fighters have managed to seize control of several neighborhoods in Aleppo since storming the city last summer.

The conflict started with largely peaceful protests against Assad's regime in March 2011 but turned into a civil war. About 93,000 people have been killed in the war, according to the United Nations.