- Annan -- a former U.N. chief -- is serving as a special envoy to Syria
- Syrian opposition activists say international meetings are not yielding results
- Protesters show solidarity with victims of Tremseh attacks, which left at least 220 dead, opposition activists say
(CNN) -- Syrian protesters Friday demanded the removal of international envoy Kofi Annan after hundreds of deaths a day earlier blamed on shelling by government forces, opposition activists said.
Annan -- a former U.N. chief -- is serving as a special envoy to Syria for the United Nations and the Arab League.
He implemented a peace plan in Syria in April, but opposition fighters and regime forces have largely shunned its mandates, including a call to lay down their weapons.
"It is clear that the Annan mission is no more than providing more time to Assad to remain in power and commit atrocities, killings and massacres," said Ahmed, an activist from Homs who did not want all his names used for safety reasons. "He is but a legitimate cover for the crimes of the Assad regime."
Protesters took to the streets at dawn in solidarity with victims of government shelling late Thursday that left at least 220 dead in the village of Tremseh in Hama province, according to the opposition Local Coordination Committees of Syria.
Regime forces targeted the village with relentless shelling for hours, leading to the "massacre," the opposition group said.
CNN cannot independently verify reports of violence in Syria because the nation has restricted access by international journalists.
If confirmed, the death toll would make it the bloodiest day in Syria since the uprising against the government started 16 months ago.
The government painted a different picture of the attacks.
In a report on state media, Syria said more than 50 people were killed in Tremseh, maintaining its stance that "armed terrorist groups" are to blame. The government said residents called security forces for help after the terrorist groups raided the neighborhood.
Regime forces arrested some of the members of the terror groups and confiscated their weapons, the government said.
The conflict in Syria has defied international peace efforts, leaving world leaders scrambling to find a solution.
On the uprising's main Facebook page, opposition leaders accused Annan of failing to stop the killing of civilians, saying Syria will be his "second Rwanda," a reference to a 1994 genocide in the African nation that killed at least 800,000.
They demanded his removal from his role as special envoy and urged protesters to make that the theme of Friday protests.
While Annan did not become the U.N. secretary general until 1997, he was in charge of peacekeeping operations for the world body at the time of the genocide in Rwanda.
President Bashar Al-Assad's bloody crackdown on civilians has sparked international outrage, but the support of allies such as Russia and China has protected the Syrian regime and hindered a resolution by the United Nations.
Russia and China, which are permanent U.N. Security Council members, have vetoed council draft resolutions that would have condemned the Syrian regime.
The U.N. Security Council on Thursday discussed dueling draft resolutions on Syria. Ambassadors remain at odds over whether a Western-backed resolution should invoke a U.N. charter mandating sanctions and ultimately lead to an authorization of the use of force.
Russian officials decried the resolution, according to state-run RIA Novosti.
"Using the resolution to justify the use of force in the future is absolutely unacceptable to us," Deputy Foreign Minister Gennady Gatilov said.
Syrian activists and political opposition groups have said the meetings are not yielding results, and urged their fighters to mobilize and intensify their efforts to oust al-Assad's regime.
"We keep hearing about the reports they keep submitting to the Security Council but to no avail and the empty promises of protecting the Syrian people, without any serious action on the ground," the Syrian National Council said in a statement. "The international institutions responsible for the international peace and security in the world are powerless."
The U.N. Security Council discussions at the ambassador level are scheduled to resume Friday.
A vote on whether to renew the mandate for the 300-person U.N. observer force in Syria past its July 20 expiration is at the heart of the discussions.
Meanwhile, the regime has suffered a series of setbacks. Syria's ambassador to Iraq defected Wednesday and joined the opposition, days after the son of a former defense minister cut ties with the regime.
CNN's Ivan Watson, Saad Abedine and journalist Shiyar Sayed Mohamed contributed to this report
