Syrian government troops backed by tanks battled to oust rebel forces from an opposition stronghold in a Damascus suburb on Tuesday in the heaviest fighting in the capital for months.

Opposition sources said elite Republican Guard troops attacked the rebel-held suburb of Daraya and were met by fierce resistance from anti-government fighters, who hung on to their positions despite days of aerial bombardment.

After months of slow progress, the rebels have captured several army positions in outlying regions in the last week, including a Special Forces base near Aleppo, Syria's commercial hub.

On the diplomatic front, the British government officially recognized the Syrian opposition coalition and will provide communications and other support to it. It became the tenth country to do so following France, Italy, Turkey and the Gulf Arab states.

Also Tuesday, Turkey's foreign minister said NATO states had agreed to supply Ankara with a Patriot missile system to defend against Syrian cross-border shelling. While the deployment would be for defensive purposes, it marks a hardening in the foreign opposition to Syrian President Bashar al-Assad.