The Syrian military entered Sunday some restive suburbs of the capital Damascus to confront what the government described as "armed terrorist groups," a witness told Xinhua anonymously.

The army has entered restive suburbs such as Douma, Harasta, Ghouta and Kafr-batna, the source said.

Earlier Sunday, an armed group targeted a military bus with a roadside bomb in the Damascus suburb of Sahnaya, killing six soldiers, including two officers, according to official SANA news agency.

Meanwhile, the Doha-based al-Jazeera TV cited activists as saying that at least 48 people were killed during the army's operations in restive neighborhoods of Damascus.

The Syrian government has blamed the country's months-long unrest on armed groups and "foreign conspiracy."

The government forces stepped up the crackdown over the past days on violence in restive areas in central Syria and Damascus suburbs, as the leadership pledged to beat "terrorists" with an iron grip.

In his recent televised appearance, Syrian President Bashar al- Assad said that "we will defeat the plot," adding that "they ( conspirators) are in their final stage."

"Restoring security is the ultimate priority for Syria at this stage," he said, "Terrorists would be beaten with an iron fist."

Syrian Foreign Minister Walid al-Moallem has recently stressed that a security solution in Syria has become a "popular demand by the Syrian people but won't be the sole solution," adding that some of the opposition figures have instruction from outside not to take part in the dialogue called for by the government.

Some Syrian provinces, including Homs, Hama and Idlib, and the suburbs of Damascus have witnessed severe clashes between the government troops and militia groups allegedly consisting of army defectors. The daily violence has sparked fears that the country might be sliding towards a civil war.

The head of the so-called Syrian Free Army, a group of alleged defectors who were given refuge in Turkey, has recently pledged to carry out wide-scale attacks against army bases across Syria.

The Syrian government said more than 2,000 army and security personnel were killed during the months-long unrest, while the United Nations put the death toll in the country at more than 5, 400.