Syrian security forces on Tuesday continued to shell the central city of Homs, killing at least four people, activists told dpa, while Arab League observers headed to the area dpa reported
The shelling, concentrated on the neighbourhood of Baba Amr, lasted overnight. Quoting hospital sources, Omar Homsi, an activist based in the area, told dpa that 60 people had been killed there since Monday and 70 wounded.
Meanwhile, the first batch of Arab observers, who arrived in Syria on Monday, left Damascus and headed to the province of Homs, an Arab diplomat in Beirut told dpa.
"Let us hope they will be able to accomplish their mission," he added.
Syria has been gripped by an uprising calling for the ouster of President Bashar al-Assad since mid-March. According to United Nations estimates, the government crackdown on protesters has killed more than 5,000 people.
Homsi meanwhile blamed an explosion at an oil refinery in Tablisa, also in Homs, on the government, saying that Syrian army helicopters were seen over the area shortly before the blast took place.
"The Syrian authorities carried out the attack to defame the nature of the peaceful uprising that started in March against this brutal regime," Homsi said.
He added that in the early hours of the morning, Syrian security forces had also stormed areas in the neighbourhood of Douma, in the capital Damascus, following anti-regime protests which took place overnight in support of the people of Homs.
The Arab League plan which was agreed on by al-Assad last week requires the government to remove its security forces and heavy weapons from city streets, start talks with opposition leaders and allow human rights workers and journalists into the country.
The 50 monitors now in the country, who include Iraqis, Tunisians and Algerians nationals, are supposed to ensure compliance, though so far there is no sign that al-Assad is implementing any of the terms.
Another 100 monitors are set to arrive by the end of December.