FRESH CLASHES HAVE broken out in Syria, with at least 19 protesters left dead.

Hundreds of thousands of Syrians poured into the streets across the nation today in the largest protests in months, shouting for the downfall of the regime in a defiant display invigorated by the presence of Arab observers, activists said.

Despite the presence of the monitors, activists said Syrian forces killed at least 19 people, most of them shot during anti-government protests.

Rami Abdul-Raham, who heads the British-based Syrian Observatory for Human Rights, said the crowds were largest Friday in Idlib and Hama provinces, with 250,000 people each. Other massive rallies were held in Daraa province and the Damascus suburb of Douma, he said.

The ongoing violence in Syria, and new questions about the human rights record of the head of the Arab League monitors, are reinforcing the opposition’s view that Syria’s limited cooperation with the observers is nothing more than a ploy by President Bashar Assad’s regime to buy time and forestall more international condemnation and sanctions.

There is broad concern about whether Arab League member states, with some of the world’s poorest human rights records, were fit for the mission to monitor compliance with a plan to end to the crackdown on political opponents by security forces.

The United Nations says some 5,000 people have been killed in the government campaign since March.

Despite skepticism over the Arab League mission, it has energized the protest movement, with tens of thousands turning out this week in cities and neighborhoods where the observers are expected to visit.

The huge rallies have been met by lethal gunfire from security forces, apparently worried about multiple mass sit-ins modeled after Cairo’s Tahrir Square. In general, activists say, security forces have launched attacks when observers were not present. But there have been some reports of firing on protesters while the monitors were close by.

The Local Coordination Committees, an activist coalition, said at least 130 people, including six children, have been killed in Syria since the Arab observers began their one-month mission on Tuesday.

The nearly 100 Arab League monitors are the first Syria has allowed in during the uprising, which began in March. They are supposed to ensure the regime complies with terms of the League plan to end President Bashar Assad’s crackdown on dissent.

The plan, which Syria agreed to on Dec. 19, demands that the government remove its security forces and heavy weapons from cities, start talks with the opposition and allow human rights workers and journalists into the country. It also calls for the release of all political prisoners.

Pro-Assad groups turned out for rallies in Damascus and several other cities, waving portraits of the president, in an apparent bid to show the regime has public support during the observer visit. On Friday, Russia’s Foreign Ministry said an initial assessment by Arab League observers in Syria was “reassuring.”

Moscow is one of Syria’s few remaining allies following more than nine months of violence.

Also Friday, the rebel Free Syrian Army said it has stopped its offensive against government targets during a month-long mission by Arab Legue monitors, saying it wants to expose how the regime is killing peaceful protesters.

The leader of the FSA, breakaway air force Col Riad al-Asaad, said his troops have halted attacks since the observers arrived. The government insists terrorists and gangs are driving nine months of crisis in Syria.

The Free Syrian Army says it is comprised of some 15,000 army defectors who abandoned the regime during the uprising. The group has claimed responsibility for attacks on government installations that have killed scores of soldiers and members of the security forces.

On Friday, activists said security forces fired on protesters in the southern province of Daraa, Hama province in central Syria and elsewhere. In the central city of Homs, six people who were reported missing Thursday were confirmed dead Friday.

Another four were reported killed in the town of Talkalakh, near the border with Lebanon, in an ambush by government troops. It was not immediately clear why they were killed as the victims were not believed to be protesting at the time, activists said.

Read: Prisoners detained during unrest released in Syria>