Arab League observers expected in Syria on Monday.

CNN - Dozens of Arab League observers are expected to arrive in Syria on Monday to determine whether the government is complying with an agreement to end a brutal crackdown -- even as an opposition group claimed security forces killed more than a dozen civilians in attacks the same day.

The arrival of the observers follows opposition reports of an increase in attacks by government forces in recent weeks that left scores dead, with numerous deaths in the hard-hit flashpoint city of Homs. Dual bombings that targeted Syria's security apparatus in the capital city of Damascus killed dozens.

About 50 observers from the Arab League will be among the first to arrive, and more monitors are expected to follow as needed, said an Arab League official. The number of observers could total almost 100, said the official, who spoke on condition of anonymity because he was not authorized to release details to the media.

The opposition Syrian National Council called on the observers to go straight to Homs, citing a "tight siege and the threat of military invasion" by 4,000 soldiers in addition to "non-stop bombing" of recent days.

"We face a real threat of genocide and crimes against humanity in Homs, whose residents are calling for help and warning of the imminent danger they face if the Arab League does not immediately send its observers there," the council said in statement.

CNN cannot independently verify opposition accounts of violence or reports of deaths and injuries in Syria. President Bashar al-Assad's government has restricted access to international journalists.

The opposition has described worsening conditions in cities and towns amid what they call an intensifying government offense. This comes at a time when security forces and allied militia fighters are supposed to be withdrawing as part of a plan to end the violence following more than nine months of protests against al-Assad's government.

The Syrian Observatory for Human Rights, a London-based opposition group, said 13 people were killed and dozens wounded Monday during shelling attacks by Syrian security forces in Homs, an opposition stronghold north of Damascus.

The Homs neighborhood of Baba Amr was particularly hard-hit, the group said.

The unrest in Syria began in March when protesters, emboldened by successful democracy movements in Tunisia and Egypt, called for open elections and an increase in political freedoms. The movement quickly spiraled into a call for the ouster of al-Assad, who the opposition says responded with a brutal crackdown.

The protests have grown into an uprising that has seen the creation of a Free Syrian Army, a rebel force made up of military defectors, and efforts to create a breakaway government.

Al-Assad has been under enormous international pressure to end the violence from the United States, the European Union, the Arab League and Turkey.

The opposition said 13 people, including three children, were killed and scores injured in government attacks across Syria on Sunday.

The worst violence occurred in Homs, said the Local Coordination Committees, an opposition network that says it collects eyewitness reports from members on the ground in Syria.

Five people were killed in the city, where government forces have laid siege to neighborhoods, the LCC said.

An opposition activist who identified himself as Abu Omar told CNN on Sunday that recent attacks by government forces began Friday and were non-stop in some besieged neighborhoods. He said the gunmen are shooting at anything and everything.

"You can't cross the street because of the snipers," Omar said. "They are cutting the electricity. Now I'm walking by a generator. There is no water or satellite phone. There is no more food, and we have missing the most important thing, which is the bread. There is no more bread ... for children."

More than 5,000 people have died since al-Assad began a brutal crackdown in mid-March on anti-government protesters calling for his ouster, the United Nations said earlier this month.

But opposition groups and political activists say the toll is much higher.

Avaaz, a New York-based political activist group, puts the toll at more than 6,000. The LCC also put the toll at more than 6,000.

The Syrian government has said 2,000 of its soldiers and security forces have been killed in the uprising, which it blames on "armed gangs."

The arrival of the observers in Syria is part of an agreement that al-Assad's government made with the Arab League last week. The agreement calls for the withdrawing of Syrian army and militias as well as rebel forces, releasing detainees and end all forms of violence.

The head of the Arab League monitoring mission, Lt. Gen. Mohamed al Dabi of Sudan, arrived in Syria with an advance team over the weekend, the Arab League official said.

Questions are being raised about what, if any, effect the Arab League observation mission will have with reports of the escalation of violence ahead of the team's arrival.

On Sunday, Egypt's main Islamist party, the Muslim Brotherhood, met Sunday with Russia's ambassador to Cairo to discuss the deteriorating situation in Syria, according to a party official.

Esam El Arian, deputy head of the Muslim Brotherhood's Freedom and Justice Party, said Ambassador Sergei Kirpichenko "expressed his country's desire to see the Syrian civilians safe in their own country."

Russia has been a supporter of the al-Assad regime.