The United States is "deeply concerned" by the situation in Homs, the State Department spokeswoman said Friday, condemning what she called the Syrian government's attacks on Homs's old city.

"We strongly condemn the regime's breaking of the cessation of hostilities, and its brutal assault against residents of old city Homs," State Department spokeswoman Jen Psaki told a press briefing.

The remarks came as the Syrian government troops launched an offensive recently against rebel-held districts in the old quarter of Homs, triggering retaliatory attacks by rebels to fend off the government's advance.

On Friday, a booby-trapped car ripped through a government- controlled neighborhood of Homs, killing at least ten people and injuring more than 20 others. Neither the Syrian government nor the rebels claimed responsibilities for such attacks, and there was no way to verify it.

Terming the government's bombardments and encirclement of the city "a despicable example of its starve and surrender battlefield approach," Paski urged the Syrian government "to cease its attacks on the old city, and allow for the delivery of humanitarian assistance."

The spokeswoman also accused the Syrian government of " intentionally increasing the desperation of the Syrian people in its all-out bid to retain personal power."

"We will continue to draw international attention to this catastrophic situation until the suffering of the Syrian people ends," she said.

Homs, Syria's third largest province, was one of the first provinces brewing protests against Syrian President Bashar al- Assad in 2011. The rebels there have taken control of broad swathes of land, but the government troops have taken back the territory over the past year.