Footage uploaded onto YouTube shows the scene outside a field hospital
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Syria crisis: Army steps up shelling in Homs

Heavy artillery fire has been rocking Homs, as Syrian troops step up an assault on the western city.

Activists say a field clinic is being targeted in one of the fiercest assaults on the city in the 11-month uprising.

Meanwhile, Russia and China defended their veto of a UN draft resolution criticising Syria - a move that angered opponents of President Bashar al-Assad.

Our correspondent Jim Muir has been watching the latest developments in Syria from neighbouring Lebanon.

Go to next video: 'They target the field hospital'