The United Nations chief has accused Syria of possible crimes against humanity as activists say Syrian security forces are assaulting the city of Daraa where the uprising began.

U.N. Secretary General Ban Ki-Moon told reporters in Vienna Thursday that he is demanding that President Bashar al-Assad's government immediately stop the “shelling and use of force against civilians.”

“We see almost certain crimes against humanity. The lack of agreement in the Security Council does not give the government license to continue this assault on its own people. The longer we debate, the more people will die.''

The London-based Syrian Observatory for Human Rights told VOA at least 24 people were killed across the country Thursday, including four people in clashes in Daraa and 14 people in a government assault on a defected area near Hama.

The U.N. General Assembly is expected to give broad support Thursday to a resolution accusing Syria of rights violations and calling on the government to stop its deadly crackdown on dissent. The document circulated by Arab diplomats is non-binding.

Britain-based activist Rami Abdul-Raham says Syrians can not wait for the international community to take action in the restive country.

“If I'm in Syria and the Syrian regime is killing my father, or my mother, or my brother, or my son. What do I need to do? I just have to wait to get support from the international community? Then maybe if I'm in Syria now, I have to take to buy a gun and join the Free Syrian Army.”

Rights groups say more than 6,000 people have been killed since pro-Assad forces began cracking down on anti-government protesters last year. The U.N. stopped updating the death toll in January, saying it was too difficult to obtain information.

Russia and China vetoed a U.N. Security Council resolution earlier this month, blocking the body from endorsing a Western- and Arab-backed plan for President Assad to step aside as a way of ending the crisis.

China said Thursday it is sending a senior diplomat to Syria for talks about the crisis. Foreign Ministry spokesman Liu Weimin said Vice Foreign Minister Zhai Jun will be in Syria on Friday and Saturday, but could not say who will be involved in the talks.

“We call on the government of Syria to seriously heed the people's legitimate desire for reform and development, and call on the various political factions to express their political aspirations non-violently under the rule of law.”

He said China wants to press for a peaceful resolution. The vice foreign minister met with a Syrian opposition delegation last week in Beijing.

Thursday's vote at the U.N. comes a day after Mr. Assad ordered a constitutional referendum for later this month that he said would end nearly five decades of single-party rule and set a presidential term limit.

“The specific timetable of the event is still being organized. I want to send a message that China hopes to push forward a peaceful and appropriate resolution to the Syria crisis. China is willing to continue playing a constructive mediation role in resolving the crisis.”