Smoke rises from what is said to be the Syrian town of Qusair after ferocious battles between rebels and Hezbollah fighters backing President Bashar al-Assad.

In another video obtained from a social media website, unidentified rebel groups fire anti-aircraft guns, apparently on the town's outskirts.

Reuters cannot independently verify the content of these videos.

Syrian activists say rebels pushed back the attacking government forces, killing about 30 Hezbollah fighters and 20 Syrian troops.

But state media reported a different version of events, saying the army had restored security to most of Qusair and cornered what they called "terrorists".

Syrian government restrictions on independent media access make it hard to verify either account.

Meanwhile, tensions are high in Lebanon's northern city of Tripoli, where the Lebanese army has deployed after the Syrian conflict once again spilled over into the city.

At least one person was killed in fig