There was no immediate word on any casualties from the hour-long morning bombardment of the city's Jurat al-Shayah and Al-Qarabis neighbourhoods, the Syrian Observatory for Human Rights said.
The Baba Amr district of Homs became a symbol of the protest movement against President Bashar al-Assad's regime launched in March last year when it came under a devastating month-long pounding before being overrun by government forces at the beginning of last month.
The UN Security Council was to vote later on Saturday on a Western-drafted resolution allowing a ceasefire observer mission in Syria even though Russia's support remained in doubt.
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The United States called for the vote after a second day of wrangling with Russia over security guarantees for the first 30 unarmed military monitors that UN-Arab League peace envoy Kofi Annan wants in Syria early next week.
