A U.N. official says international envoy Kofi Annan left Syria without securing any major steps from the Syrian government to implement his faltering peace plan for the country.

Mr. Annan discussed the Syrian crisis with Jordanian officials in Amman, Jordan, after flying out of Damascus Wednesday.

While in Syria, the U.N.-Arab League envoy made a personal appeal to Syrian President Bashar al-Assad for “bold steps” to create momentum for peace “now, not tomorrow.”

Speaking by phone from Damascus, U.N. spokeswoman Sausan Ghosheh said Wednesday she was not aware of any action by the Syrian government.

Mr. Annan's plan called on the Syrian government to withdraw heavy weapons from civilian areas and abide by a truce with rebels. But attacks by both sides have continued.

Syrian activists said fighting between government and rebel forces on Wednesday killed at least nine people, five of them in the Damascus suburb of Douma. They said government troops shelled Douma and the central city of Homs, also an opposition stronghold. The casualties could not be independently confirmed.

The U.N. observer mission in Syria confirmed the killings of 13 people in the northeastern province of Deir el-Zour. The mission said U.N. monitors found the bodies late Tuesday, with some of the dead appearing to have been shot in the head from short range and all having their hands tied behind their backs.

U.N. observer chief Robert Mood, a Norwegian general, said he is “deeply disturbed by this appalling and inexcusable act.” He also called on all parties “to exercise restraint and end the cycle of violence.”

International outrage has mounted since a massacre of more than 100 residents took place in the central town of Houla last Friday.

Israeli Defense Minister Ehud Barak urged the international community to take tougher action against Mr. Assad's government for what he called its “crimes against humanity.”

“The events in Syria mean the world must take action, not only by talking, but by acting. These are crimes against humanity, and it is impossible that the international community stand aloof.”

Japan and Turkey said Wednesday they are expelling Syrian diplomats in protest of the Houla incident.

Nine Western nations announced expulsions on Tuesday, including the United States, Australia, Britain, Canada, France, Germany, Italy, the Netherlands and Spain. The Syrian government retaliated on Wednesday by ordering the Dutch charge d'affaires to leave Syria within 72 hours.

Diplomats in Geneva said the U.N. Human Rights Council plans to hold an emergency meeting on Friday to discuss the Houla massacre. They said the United States, Turkey and Qatar led the push for the special session.

The U.S. Treasury on Wednesday also announced it will freeze the assets of the Syrian International Islamic Bank to tighten economic pressure on the Syrian government.

Russia and China restated their opposition to any military intervention in Syria, a day after French President Francois Hollande said he does not rule out such action if the U.N. Security Council approves it.

Russian Deputy Foreign Minister Gennady Gatilov told the Interfax news agency that Moscow will veto any Council resolution that authorizes foreign military interference in Syria, a longtime Russian ally. He also said it is “premature” for the Council to consider any new measures to deal with the Syrian crisis.

In Beijing, foreign ministry spokesman Liu Weimin said China opposes regime change by force in Syria. He also said he is not aware of any Chinese move to expel or disrupt the work of Syrian diplomats in the country.

The Security Council is expected to meet later Wednesday to hear an update from the U.N. mission on Mr. Annan's efforts.