A group of Arab League monitors visited the Syrian city of Homs again Wednesday, while less than 50 kilometres away activists reported that several protesters were shot and killed by government troops.

Six people were shot to death in the central city of Hama when troops opened fire on a demonstration, activists said, bringing the death toll since the Arab League mission arrived in Syria two days ago to 39.

The continuing violence has led Syria's main opposition group to cast doubt on the effectiveness of the Arab League monitors, who are supposed to ensure the regime of President Bashar Assad is complying with a plan to end its violent, months-long crackdown against anti-government protesters.

"This mission has absolutely no mandate, no authority, no teeth," said Ausama Monajed, a member of the Syrian National Council, the main opposition group. "The regime does not feel obliged to even bring down the number of casualties a day."

The opposition suspects Assad is trying to buy time and forestall more international sanctions while regime forces attempt to stifle anti-government demonstrations, which have spread to around 10 cities.

About 60 observers are in Syria to oversee an Arab League agreement in which the Syrian regime said it would end its military crackdown on the popular uprising, which began last March.

The monitors are touring the country's most volatile cities, ostensibly to ensure the army is withdrawing, but activists said they're concerned the teams may not be getting a true picture of the crisis.

Dissidents in the flashpoint city of Homs met with a few of the Arab League monitors on Wednesday, activists told Reuters.

When the delegation arrived in Homs on Tuesday, dissidents accused the government of trying to persuade the Arab League that all was calm on the streets by removing some tanks from the city and ending a three-day military shelling campaign in Baba Amr.

“Some places looked a bit of a mess but there was nothing frightening,” said Sudanese Lt.-Gen. Mustafa Dabi, the head of the Arab League team. He also called the month-long mission "reassuring so far."

The UN said about 5,000 people have been killed since the crackdown on dissidents began and more than 14,000 people have been arrested and placed in detention.

Prisoners reportedly released

On Wednesday, Syrian state TV said the authorities have released 755 people detained during the uprising against President Bashar Assad.

The prisoners had been involved "in recent incidents" but their "hands were not stained with blood," the television report said.

Under the Arab League agreement, all detained protesters should be freed.

The New York-based group Human Rights Watch had accused Syrian authorities of hiding hundreds of detainees from the observers by transferring them to off-limits military sites. It also said the government was issuing police identification cards to military personnel and dressing soldiers in police uniforms.

State TV, meanwhile, aired footage Wednesday showing an alleged weapons cache that government officials say was recently uncovered. It's a development that "furthered their narrative that they're fighting these armed terrorist gangs," Time magazine correspondent Rania Abouzeid said from Beirut.

"On the other side of the divide is the activists' version that they're up against these merciless security forces that are shelling and firing at unarmed civilians," Abouzeid said.

With files from The Associated Press