At least 20 people have been killed in violence in Syria, following one of the deadliest days of the seven-month-old uprising against the Syrian government.

Activists say at least three people died Saturday when security forces launched raids in the rebellious city of Homs. Witnesses say heavy shelling could be heard in the central district as government forces in armored vehicles pushed into the area.

The Syrian Observatory for Human Rights says 17 soldiers were killed earlier in overnight clashes with suspected army deserters.

The United Nations and Arab League condemned the violence. U.N. Secretary-General Ban Ki-moon urged Syria to halt military operations.

On Friday, security forces killed at least 40 people as anti-government protesters rallied in the country. Activists say most of the deaths occurred in the Homs and Hama regions.

On Sunday, Arab League ministers plan to meet with Syrian officials to discuss ways to end the deadly violence resulting from anti-government protests.

Syrian President Bashar al-Assad has been facing growing international condemnation for his crackdown on opposition protesters. The United Nations says the death toll from seven months of anti-government protests has topped 3,000.