Story highlights U.S. envoy Susan Rice: "It's possible that not everybody will have instructions"

The council is seeking to expand the size of a monitoring mission

The vote would come amid violence, which continues despite a cease-fire

Opposition group: At least 57 people are killed in Syria on Friday

The U.N. Security Council is expected to meet Saturday and vote on a resolution that would expand the size of a U.N. monitoring mission in Syria, Western diplomats said.

The text of the draft calls for the immediate implementation of a six-point peace plan, as put forward by U.N.-Arab League envoy Kofi Annan, and demands all parties, including the opposition, stop the violence. It would further authorize the deployment of up to 300 unarmed military observers, who would be expected to ensure compliance with a shaky cease-fire imposed last week.

The resolution represents the merger of Western and Russian texts, the diplomats said. The vote is scheduled for 11 a.m. ET, they added.

However, Security Council President Susan Rice, who is also the U.S. ambassador to the United Nations, advised caution late Friday.

"If council members are in a position to vote, we are aiming to do so tomorrow around 11. It's possible that not everybody will have instructions at that point," she told reporters.

The 15-member Security Council previously approved the deployment of an advance team of 30 monitors meant to pave the way for a larger group of observers.

U.N. Secretary-General Ban Ki-moon has called for the initial three-month observer mission to be expanded to 300 monitors in 10 locations, and asked the Security Council to authorize the expanded number.

A handful of observers are already in Syria; more are expected soon.

"We have seven observers on the ground today, two more are arriving on Monday to bring those on the ground to nine ... (and) we will make the numbers up to 30 some time during the course of next week," said Ahmad Fawzi, spokesman for Annan.

He said the observers in the country have not yet been to Homs, which has been a hotbed for dissent and bloodshed in recent months.

"The situation on the ground is not good, as we all know," Fawzi said. "It's a very fragile cease-fire. There are casualties every day. There are incidents every day and we have to do everything we can to stop what's going on: the killing, the violence in all its forms."

Russia -- which has blocked action against the Syrian regime -- called for the quick approval of the Security Council resolution to deploy more monitors.

"Every effort should be made to get a second resolution passed that would approve a full-scale monitoring mission and, simultaneously, influence all groups in Syria without exception into cooperating for the sake of implementing the Annan plan," Russian Foreign Minister Sergei Lavrov said at a news conference Friday in Moscow.

Syria and the United Nations reached agreement Thursday on a protocol for the advance monitoring team and other observers. It outlines the functions of the observers, and the tasks and responsibilities of the Syrian government, according to Annan.

Russia said a Syrian opposition delegation will visit Moscow next week.

Meanwhile, China said it will send observers to join the U.N. monitoring mission, the state-run China Daily newspaper reported, citing a foreign ministry spokesman.

The expected U.N. vote would come one day after Syrian protesters gathered for demonstrations that were met with armed resistance from government forces, opposition groups said.

Security forces in Aleppo used gunfire and tear gas on demonstrators, injuring four, the London-based Syrian Observatory for Human Rights reported.

In Daraa province, forces fired at protesters to disperse them, said the Local Coordination Committees of Syria, another opposition group.

Meanwhile, the government blamed terrorists for exploding a bomb that killed 10 troops in the region of Quneitra.

In all, 57 people were killed across Syria on Friday, the coordination committees said. Twenty-one people were killed in Homs, 10 in Idlib, seven in Damascus, seven in Aleppo, six in Damascus suburbs, four in Bokamal and two in Daraa, the group said.

Security forces also raided homes in a neighborhood in the capital of Damascus.

"Fear is spreading among the residents after arrival of military reinforcements and heavy security deployment," the opposition group said in a statement.

In the northern Syrian town of Binnish, there were four men at a protest wearing camouflage uniforms with the letters "U.N." embedded on them. They were not real U.N. observers, however, but demonstrators who were mocking the tiny six-man U.N. mission in the country so far.

"We demonstrated dressed up like this in the streets to inform the world what is happening to us and to make them pay attention to what is happening in Binnish and this region," one of the costumed protesters told CNN by phone. He gave his name only as Ahmed.

"We also wanted to show the world the mockery that (Syrian President) Bashar al-Assad is making of the United Nations and the world," he said.

The costumed protesters walked around with paper and cotton sticking out of their ears. They did so, Ahmed explained, "because the world is not listening and acting deaf and refusing to listen."

CNN cannot independently verify reports of violence and deaths as the government has severely restricted access by international media.

The international community is seeking an end to the bloodshed, but the Security Council is split between Western countries demanding tough measures against al-Assad, and Russia and China, which have blocked action against the regime.

While violence ebbed after the truce began last week, Ban said, it resumed days later and Syria has not lived up to its promise to withdraw troops from cities, a key element of the peace plan.

The plan calls on both sides to end the violence, allow access to humanitarian groups, release detainees and begin a political dialogue.

It also says demonstrators should be able to protest peacefully. While there was a restrained regime response to demonstrations a week ago, Ban said, there were attempts to intimidate protesters, including reports of gunfire by government troops.

There has also been no significant release of detainees and no substantive progress on providing humanitarian assistance, another point of the peace plan, Ban said.

Syria has been engulfed in violence for 13 months as a national uprising has spread, and the government has cracked down on peaceful protests. The United Nations estimates that at least 9,000 people have died since the protests began, while activist groups put the death toll at more than 11,000.