Mortar shells struck a residential area in central Syria Wednesday, killing three people and wounding more than 50, including a number of women and children, state-run news agency said.

The latest mortar attacks came as Syrian regime troops fought fierce battles with revolution forces for control of key neighborhoods in the northeast of the capital, residents and activists said.

Revolution forces have stepped up mortar attacks on Damascus in recent weeks, striking deeper than ever into the heart of the city in a new tactic to try and loosen Assad's grip on his main stronghold.

Also, a European Union staff member was killed in a rocket attack on a revolution stronghold south of the capital, the EU said.

Revolution forces have been trying to advance into Damascus for weeks, battering regime checkpoints and military bases in the heavily fortified capital.

The Syrian Observatory for Human Rights said Wednesday's clashes were concentrated in the capital's neighborhoods of Jobar and Barzeh.

A resident in the area said shelling overnight "shook apartments" and terrified the inhabitants.

He spoke on condition of anonymity because he feared for his safety.

A car bomb exploded outside a police station in Khan Sheih neighborhood, west of Damascus, the Observatory said. The Britain-based activist group also said fierce clashes broke out after the blast but had no immediate reports of casualties.

Fighting also raged in other Syrian cities, including Homs, where the military pounded the area with artillery and carried out several airstrikes on the Baba Amr district, a former revolution.

In Brussels, EU foreign policy chief Catherine Ashton said a policy officer with the European delegation in Syria was killed on Tuesday in the Damascus suburb of Daraya. It was the first death of an EU employee in the Syrian war.

Ahmad Shihadeh, 32, worked for the EU for five years, a spokesman for Ashton said Wednesday. He said Shihadeh had lived in Daraya, a suburb of Damascus that has been one of the main battlefields in the capital.

Ashton said he "died while providing humanitarian help to the community of Daraya," Ashton said. "Ahmad was known for his courage and selflessness."

Ashton took the occasion to call for an end to the conflict, which started in March 2011 as protests against Assad's authoritarian rule. The revolt turned into armed opposition to fight back a harsh government crackdown on its people.

According to U.N. figures, more than 70,000 people have been killed in the 2-year-old conflict and four millions Syrians driven from their homes. There was no immediate explanation of Aston's higher death toll.

PHOTO CAPTION

Two Syrian brothers Bashar, 12, left, and Rasem, 14, right, who fled their home from Hassakeh, try to sell flowers to make a living in Beirut, Lebanon, Wednesday, March 13, 2013.

AP