Heavy weapons have been pulled from Syrian cities and about 3,500 prisoners are free but violence in the country persists, the Arab League chief warned Monday.

Despite some concessions, Arab League Secretary General Nabil Elaraby said Syrian President Bashar Assad's security forces are still firing on protesters and snipers continue to operate.

Monitors entered the country last Tuesday to keep an eye on Assad's compliance with an Arab-brokered peace plan which demands that Syria free political prisoners and start talks with opposition leaders, among other conditions.

Even with observers present, Elaraby said the threat of gunfire lingers in Syrian cities.

"Yes, killings continue," he told reporters at a news conference in Cairo Monday. "The mission's philosophy is to protect civilians, so if one is killed, then our mission is incomplete."

Activists estimate that pro-regime forces have killed more than 150 people since monitors entered the country, casting doubt on the mission's effectiveness.

Abdul Omar with the British-based Syrian Observatory for Human Rights has called on the League to declare the Syrian mission a failure.

In an interview with Â鶹´«Ã½ Channel, he urged the Arab coalition to seek an international solution to Assad's bloody crackdown in Syria, which has been ongoing for approximately nine months.

The Arab Parliament has also been critical of the mission, dismissing it as allowing Assad a cover for violence perpetrated by his regime.

During his conference, Elaraby acknowledged the ongoing violence in Syria and called for a ceasefire within the country.

But he also listed a number of successes he says observers have achieved while in the country. Among them were that tanks and heavy artillery have been pulled from cities and food supplies have reached residents.

Senator Romeo Dallaire, who has drawn parallels between violence in Iran and Syria and the Rwandan Genocide, said it may take months for the country to inch towards noticeable change.

"I think Syria is more going to be an attrition exercise than one of spontaneous revolution," he told Â鶹´«Ã½ Channel on Monday.

Dallaire said developed countries such as Canada can help end the Syrian crackdown by being more engaged diplomatically and isolating Assad -- a formula that Foreign Affairs Minister John Baird claims to be following.

In late December, Baird said Canada intends to "put the squeeze" on Assad's regime with a new set of sanctions which prohibit any imports from Syria with the exception of food.

More than 5,000 Syrians have been killed by forces loyal to Assad's regime during protests against his rule.

With files from The Associated Press