The Syrian army battled military defectors and armed opponents of the government for a second day Tuesday, in a sharp increase in violence that human rights groups say has killed as many as 150 people over two days, with some citing a much higher figure.

The fighting has centered on villages near the northwestern city of Idlib, said Wissam Tarif, an activist with the rights group Avaaz. He said that he had spoken to local activists and medical groups who put the death toll in that area Tuesday at 269 — 97 security forces and nine civilians, with the rest defected soldiers who had staged ambushes against the army.

Capt. Ahmed al-Hasan, a member of the group of defected soldiers and armed protesters known as the Free Syrian Army, said that 80 defected soldiers were killed Tuesday. Hasan spoke by phone from the town of Qusayr, near Homs.

An activist who gave his name as Osama Dughaim said via Skype that he was close to Jabal Zawia, an area near Idlib that has seen the fiercest fighting. Both his village and the nearby area were surrounded by army tanks, he said, adding that people under attack whom he had spoken to Tuesday reported 150 deaths. The army was shelling the area, he said.

Syria restricts journalists’ access, making independent verification or assessment of conflicting accounts difficult.

The escalation came as the most significant opposition group outside Libya called for other countries to intervene by establishing safe zones and declared support for an armed resistance group.

The Syrian National Council, or SNC, issued a statement in Tunisia at the conclusion of its first conference that included recognition of the role of the Free Syrian Army.

The strong line taken by the group marked an attempt to bridge the distance between the opposition-in-exile and those on the ground who have participated in nine months of protest that the United Nations estimates has killed 5,000 people, said Amr al-Azm, an activist and professor at Shawnee State University in Ohio.

Politically, the group must balance building up credibility with Western governments, the United Nations and the Arab League, who stress nonviolence and the importance of protecting minorities, and preserving its relevance to protesters within Syria who have called repeatedly for NATO intervention against President Bashar al-Assad’s government, a no-fly zone and arming of the opposition.

Omar al-Khani, an opposition activist in Damascus, said that the council had been “very slow in dealing with the events of the revolution.”

“We have no time,” he said. “Every moment, there is a martyr.”

The fresh violence, said Andrew Tabler of the Washington Institute for Near East Policy, could be an attempt by Assad’s government to quell the uprising as plans are made for international monitors to enter Syria in line with an Arab League agreement.

Tabler added that the increasing militarization of the revolt and the exiled opposition’s growing support for armed action creates a policy dilemma for the United States.

“We don’t have a policy for dealing with the fact that many people are taking up arms,” he said.