A mortar attack on the Damascus Opera House has killed two people, as regime forces intensify their campaign against rebels on the Syrian capital's outskirts.

"Two people were killed and five others wounded by a mortar round that hit the Damascus Opera House" near key government and military buildings on Umayyad Square, the official SANA news agency said on Sunday.

The Opera House, officially called the Assad House for Culture and Arts, is located near a cluster of government and security buildings. The building, which was inaugurated by President Bashar al-Assad in 2004, was the venue for a defiant speech he made last year vowing to continue fighting rebels seeking his overthrow.

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Rebels holed up in the city's rural periphery have focused their efforts on hitting the area, an activist who uses the name Muaz al-Shami told the Associated Press news agency.

Syrian rebels often fire mortar shells into Damascus from outlying communities, but the fire has recently intensified as pro-Assad forces advance on the rural Ghouta suburb to the capital's east, a long-held opposition area, Shami told AP in a Skype interview from the area.

"They [rebels] are trying to shell security strongholds in Damascus. It's an attempt to reduce pressure on the neighbourhood," he said.

Pro-Assad forces began fighting hard to seize Ghouta over the past five days, Shami said. As he spoke, explosions could be heard in the background.

The assault on Ghouta is part of a push by Assad forces to solidify its hold on Damascus by dislodging rebels from the towns and neighbourhoods on the city's fringes.

'Secret lines'

Last week government forces seized the outskirts of the town of Mleiha, near the Ghouta area. The government's gain came after pro-Assad forces severed important rebel supply lines from the eastern Lebanese border into the Damascus periphery.

Shami said rebels still had "secret lines" that allowed in food and weapons, and that they were making some projectiles in rudimentary workshops within the neighbourhood.

On Saturday, mortar rounds struck near the Russian embassy, said the Syrian Observatory for Human Rights, a London-based group monitoring the developments in the country.

Rebel fire on Damascus has wounded at least 22 people in recent days, as government forces step up a campaign to crush insurgents in its eastern suburbs, the Observatory said.

Source: Agencies