A gas pipeline in central Syria has been hit by an explosion in an attack the government blamed on terrorists, the state-run news agency said.
The blast happened near the town Rastan in the restive Homs province, Sana reported. No-one was injured.
There have been several pipeline attacks since the Syrian uprising began in mid-March, but it is not clear who is behind them - they have come at a time when violence across the country is spiralling out control, unearthing long-standing grievances and resentments.
While the government blames saboteurs and terrorists for the blasts, the opposition accuses the regime of playing on fears of religious extremism and terrorism to rally support behind President Bashar Assad, who has portrayed himself as the only force that can stabilise the country. Syria has banned most foreign journalists from the country and prevented independent reporting, making it difficult to confirm claims from either side.
Opposition groups have been deeply critical of the mission, saying it is simply giving Mr Assad cover for his crackdown. "The Arab League has fallen victim to the regime's typical traps, in which observers have no choice but to witness regime-staged events, and move about the country only with the full knowledge of the regime," said a statement by the Local Co-ordinating Committees, an umbrella group of activists.
"This has rendered the observers unable to work or move independently or in a neutral manner," the group said.
The UN estimates more than 5,000 people have been killed since the revolt erupted in mid-March. Activists say that in the week since the observers started their work in Syria on December 27, hundreds have died. The LCC put the death toll at more than 390 people since December 21.
"Yes, there is still shooting and, yes, there are still snipers," Arab League Secretary-General Nabil Elaraby told a news conference in Cairo on Monday. "Yes, killings continue. The objective is for us to wake up in the morning and hear that no-one is killed. The mission's philosophy is to protect civilians, so if one is killed, then our mission is incomplete. There must be a complete ceasefire."
Mr Elaraby stressed the achievements of the Arab League mission, saying Syria's government has pulled tanks and artillery from cities and residential neighbourhoods and freed some 3,500 prisoners. He said food supplies have reached residents and the bodies of protesters have been recovered.
While most of the violence reported early in the uprising involved Syrian forces firing on unarmed protesters, there are now more frequent armed clashes between military defectors and security forces. The increasing militarisation of the conflict has raised fears that the country is sliding toward civil war. The LCC said 20 people were killed across the country on Monday, including 11 in volatile Homs province in central Syria and three in Idlib province, which borders Turkey.