BBC News with Iain Purdon

Turkey says it wants to build an international coalition to make Syria stop its

onslaught

on opposition strongholds like the city of Homs. The Turkish foreign minister said his government was ready to host an international conference. Sebastian Usher reports.

International diplomatic efforts on Syria hit a major

roadblock

with the veto by Russia and China of a UN Security Council resolution on Saturday. But with the images of death and destruction from Homs in recent days, calls for international action to stop the killing have only grown more urgent. Turkey is now trying to keep up the pressure on President Assad. The Foreign Minister Ahmet Davutoglu has proposed an international conference hosted by Turkey, saying that if the UN Security Council can't protect civilians, then

like-minded

countries should get together to do so. He's now heading to the US for talks although it's not clear what new plan of action Turkey is advocating.

Meanwhile, in the city of Homs, residents say the Syrian army has been mounting its heaviest bombardment so far. The BBC's Paul Wood has recently left Homs.

If I was to use one word to

sum up

the mood as we left, it would be despair, people absolutely terrified. You know, we heard the army is coming, the army is using chemical weapons or this kind of thing absolutely beside themselves, and that is the effect that constant shelling produces. We counted hundreds of what appear to be tank shells and heavy artillery shells, hundreds of mortars. They are using airburst shells as well. No doubt there's a lot of sniper fire, and it appears to be