U.N. Secretary-General Ban Ki-moon warned the Security Council Thursday that all-out civil war is imminent in Syria while his predecessor Kofi Annan called again for more pressure on Damascus to halt the violence.

Annan, the special envoy of the U.N. and Arab League, said he wanted Iran to be involved in any solution to the conflict, The Daily Star of Beirut reported, a suggestion the United States immediately balked at.

The Syrian opposition and Western and Gulf nations seeking President Bashar al-Assad's ouster increasingly see Annan's six-point peace plan as doomed because of Syria's consistent use of military force to crush an increasingly militarized opposition, Reuters reported.

Western Security Council diplomats said the message from Annan and Ban at the United Nations was clear: It was time to hit Assad's government with sanctions.

The Syrian people are bleeding, Ban told reporters after addressing the Security Council. They are angry. They want peace and dignity. Above all, they all want action.

The danger of a civil war is imminent and real, he said, adding that terrorists are exploiting the chaos.

The U.N.'s official News Centre said Ban will soon put forward a new range of options for Syria. 

Both Ban and Annan strongly condemned a reported massacre of at least 78 people Mazraat al-Qubeir and acknowledged that Annan's peace plan was not working. Thursday marked the first time Annan said publicly that Syria was not implementing his plan.

Ban said U.N. monitors hoping to investigate the slaughter were denied access to the village.

They are working now to get to the scene, he said. And I just learned a few minutes ago that while trying to do so the U.N. monitors were shot at with small arms.

He also said U.N. observers have faced heavy weapons, armor-piercing bullets and surveillance drones blocking their mission, Agence France-Presse reported.  

Syrian U.N. Ambassador Bashar Ja'afari told the General Assembly the new report was truly an atrocious massacre. It is unjustifiable. Syria's government has blamed recent atrocities on the opposition and Islamist extremists it calls terrorists.

Annan confirmed to reporters he was proposing a new contact group that would include Russia, China, the United States, Britain, France and key regional players with influence on Syria's government and the opposition such as Iran. Diplomats said he would also include Saudi Arabia, Qatar and Turkey, which are backing the uprising.

U.S. Ambassador Susan Rice made clear Washington has problems with such a contact group.

Iran is part of the problem in Syria at the present, she said. There's no question that it is actively engaged in supporting the government in perpetrating the violence.

Annan did not, however, bring up the contact group idea during the council session, diplomats said, adding that he was discussing it with individual delegations instead.

Arab League chief Nabil Elaraby, who also addressed the Assembly, called on all Arab states to recall their ambassadors and halt all diplomatic contact with the Syrian government.